Learn Hardcore Russian: Современная молодёжь часто учится танцам по видео в интернете. - Modern young people often learn dances from videos on the internet.

учить (кого? чему?) – to teach or to learn/memorize something specific
- Я учу слова. – I’m learning/memorizing words.
- Он учит детей. – He teaches children.
учиться (чему?) – to study / to learn as an activity; to be learning a skill
- Я учусь танцам. – I’m learning (studying) dance(s).
- Она учится в университете. – She studies at the university.

In the sentence молодёжь учится танцам, the youth are learning for themselves, so we use the reflexive verb учиться, not учить.

Why is танцам in the dative case?

The verb учиться always takes the dative case for what you are learning:

учиться чему? – to learn what?

So:

учиться танцам – to learn (the) dances
учиться русскому языку – to learn the Russian language
учиться программированию – to learn programming

Танцы in nominative plural becomes танцам in dative plural. That’s why the form is танцам.

What is the difference between учиться танцам and учиться танцевать?

Both are possible, but there is a nuance:

учиться танцам – literally to learn (the) dances as a subject/discipline
- Slightly more “school-like”: like learning specific dance styles or dance as an art.
учиться танцевать – to learn to dance (emphasis on the ability/action)
- Focus on acquiring the skill of dancing in general.

In the sentence учится танцам по видео, the idea is closer to “learning dance / dance styles from videos”, which fits танцам well. But учится танцевать по видео would also be natural and common.

What does по mean in по видео, and why is it used here?

In this context по roughly means by / through / using / from and often appears with media or communication channels:

по телевизору – on TV
по радио – on the radio
по телефону – by phone
по видео – from/using video

Here учиться танцам по видео means something like learn dancing by (watching) videos.

Grammatically, по usually takes the dative case, but видео is an indeclinable noun (its form doesn’t change), so you don’t see the case ending.

Why is видео in singular when the meaning is videos (plural)?

Видео is an indeclinable neuter noun borrowed from English. It:

doesn’t change its form for number or case
can mean one video or videos in general, depending on context

Examples:

Я смотрю видео. – I’m watching a video / I watch videos.
Он зарабатывает на видео в интернете. – He makes money from videos on the internet.

In учится танцам по видео, we understand it as from videos or by video in a general sense.

Why do we say в интернете and not на интернете?

With интернет, the fixed, idiomatic expression is в интернете (literally “in the internet”):

сидеть в интернете – to be online, surf the internet
искать информацию в интернете – to look for information on the internet

Russian uses в with many “virtual spaces” seen as environments:

в сети – on the (net)work / online
в чате – in a chat
в приложении – in the app

We do use на with some web-related nouns, but usually more concrete “places”:

на сайте – on the website
на форуме – on the forum
на странице – on the page

So в интернете is the standard, natural collocation.

Why is the adverb часто placed before учится? Can it move?

Neutral, default word order puts часто immediately before the verb it modifies:

молодёжь часто учится… – youth often study/learn…

You can move часто, but the nuance or emphasis changes:

Современная молодёжь учится танцам по видео в интернете часто.
– possible, but sounds a bit heavy; часто is now more emphasized, sometimes with a “too often” feel.
Современная молодёжь учится часто танцам по видео…
– unusual and awkward.

Most natural options keep часто close to the verb:

Современная молодёжь часто учится танцам по видео в интернете.
Современная молодёжь учится танцам по видео в интернете довольно часто.

So the given position is the standard, most natural one.

Why is the adjective современная placed before молодёжь? Could we say молодёжь современная?

In Russian, adjectives normally come before the noun:

современная молодёжь – modern youth
русский язык – Russian language

You can say молодёжь современная, but it sounds more like you’re contrasting this youth with some other kind (old-fashioned, previous generation, etc.), or making a comment:

Молодёжь современная, совсем другая. – The youth today, they’re completely different.

In the neutral descriptive sentence, современная молодёжь is the correct and natural order.

Is интернет a proper noun here? Should it be capitalized?

In modern Russian usage, интернет is usually written with a lowercase i:

в интернете, по интернету

Historically, it was sometimes capitalized (Интернет) as a proper name, but now lowercase is more common and considered standard in everyday writing.

So in по видео в интернете, интернете with a lowercase и is normal.

Why is the verb учится in the present tense? The sentence describes a general habit, not something happening right now.

In Russian, the present tense of imperfective verbs (like учиться) is used both for:

Actions happening now
- Он сейчас учится. – He is studying right now.
Repeated / habitual actions, general truths
- Молодёжь часто учится танцам по видео. – Young people often learn dances from video.
- Вода кипит при 100 градусах. – Water boils at 100 degrees.

So the present tense here expresses a regular, typical behavior, not just a momentary action.

Could we say учится танцам из видео instead of по видео? What’s the difference?

You could say из видео, but it sounds less idiomatic in this context.

по видео – natural, standard way to say by video / from video as a medium or channel.
из видео – literally from (out of) a video, emphasizes the video as a source or container of information.

For media, Russian strongly prefers по:

учиться по книге – learn from a book
по учебнику – from the textbook
по видео – from video

So учится танцам по видео в интернете is the most natural phrase here.

Why is there no preposition before танцам (like to or for), even though English says learn dances?

Russian doesn’t need a preposition here because the verb учиться directly governs the dative case:

учиться чему? – to learn what? (dative)

So:

учиться танцам – learn dances
учиться музыке – learn music
учиться математике – learn mathematics

English uses word order and sometimes a preposition (learn to dance), but in Russian the case ending on танцам already shows the relationship, so no extra preposition is required.