Перед вебинаром не забудь включить камеру.

Because перед requires the instrumental case when it means before or in front of.

So:

• вебинар = webinar
• перед вебинаром = before the webinar

The ending -ом is the regular instrumental singular ending for many masculine nouns.

Examples:

• перед уроком = before the lesson
• перед встречей = before the meeting
• перед домом = in front of the house

In this sentence, перед вебинаром is a time expression: before the webinar.

No. Перед can be used both:

1. Temporally: before

   • перед вебинаром = before the webinar

2. Spatially: in front of

   • перед домом = in front of the house

The case stays the same: instrumental.

So the meaning depends on context.

Because не забудь means don’t forget.

• забудь by itself means forget!
• не забудь means don’t forget!

This is a very common Russian pattern:

• Не забудь позвонить. = Don’t forget to call.
• Не забудь закрыть дверь. = Don’t forget to close the door.

So in your sentence:

• не забудь включить камеру = don’t forget to turn on the camera

Забудь is the informal singular imperative of забыть.

That means it is used when speaking to:

• one person
• in an informal way

So this sentence is addressed to you singular, informal: Don’t forget...

Related forms:

• не забудь = don’t forget (to one person, informal)
• не забудьте = don’t forget (to several people, or one person formally)

Because включить is perfective, and after не забудь Russian usually uses the perfective infinitive when talking about a single complete action.

Here, turning on the camera is one specific action that needs to be done once.

• включить = to turn on, to switch on, to activate (completed action)
• включать = to turn on, to be turning on, to turn on regularly/habitually (process or repeated action)

So:

• Не забудь включить камеру. = Don’t forget to turn on the camera.

That sounds natural because you mean one specific action before the webinar.

Because камера is the direct object of включить.

You are turning on what?
→ камеру

That makes it accusative.

For feminine nouns ending in -а, the accusative singular often changes -а to -у:

• камера → камеру
• книга → книгу
• лампа → лампу

So:

• включить камеру = to turn on the camera

Russian does not have articles like the or a/an.

So вебинар can mean:

• a webinar
• the webinar

And камера can mean:

• a camera
• the camera

The exact meaning comes from context.

In this sentence, English naturally uses the:

• Before the webinar, don’t forget to turn on the camera.

But Russian simply says:

• Перед вебинаром не забудь включить камеру.

Because Russian often omits subject pronouns when they are already clear from the verb form.

Here, не забудь already shows that the sentence is addressed to you singular, informal.

So ты is understood automatically.

You could say:

• Ты не забудь включить камеру.

But that usually adds emphasis or contrast. In normal speech, Russian usually leaves ты out.

Yes. Russian word order is more flexible than English.

For example, these are all possible:

• Перед вебинаром не забудь включить камеру.
• Не забудь включить камеру перед вебинаром.
• Камеру не забудь включить перед вебинаром.

They all mean roughly the same thing, but the emphasis changes:

• Перед вебинаром... puts the time first
• Не забудь... puts the reminder first
• Камеру... emphasizes the camera specifically

The original sentence sounds very natural.

Sometimes, but not always with exactly the same feel.

• перед вебинаром = before the webinar, often meaning right before or in the period just before it
• до вебинара = before the webinar, but often more like prior to or by the time of

In this sentence, перед вебинаром sounds especially natural because turning on the camera is something you do shortly before the webinar starts.

So:

• Перед вебинаром не забудь включить камеру. = the most natural choice here

In this context, включить камеру means to turn on your camera for an online meeting or webinar.

It is a very common modern expression in Russian for video calls.

Depending on context, it can mean:

• switch on the device’s camera
• activate the webcam
• turn your video on

So in online communication:

• включить камеру = turn on the camera
• выключить камеру = turn off the camera

You would change не забудь to не забудьте.

So:

• Перед вебинаром не забудь включить камеру.
  = informal, to one person

• Перед вебинаром не забудьте включить камеру.
  = formal to one person, or informal/formal to several people

The rest of the sentence stays the same.

A helpful approximation is:

Pered vebinárom ne zabúd' vklyuchít' kámeru.

A few stress points:

• перед
• вебинАром
• не забУдь
• включИть
• кАмеру

A few pronunciation notes:

• включить is tricky because of вкл at the start
• the final дь in забудь is soft
• unstressed о is often pronounced closer to a in Russian speech

So if you say it smoothly: Перед вебинаром не забудь включить камеру.

It is grammatically an imperative, so it has the form of a command, but in meaning it is usually a friendly reminder.

Не забудь... often sounds softer than a direct command like:

• Включи камеру. = Turn on the camera.
• Не забудь включить камеру. = Don’t forget to turn on the camera.

So this sentence sounds natural, polite, and practical rather than harsh.