Learn French: Il me semble que ton opinion est évidente. - It seems to me that your opinion is obvious.

This is the core difference in this lesson! The phrase Il me semble que expresses a personal certainty or belief, so it takes the indicative mood (est). If the sentence dropped the me and just said Il semble que, it would introduce an objective uncertainty or doubt, requiring the subjunctive: Il semble que ton opinion soit évidente.

Opinion is a feminine word. Why does the sentence use the masculine possessive adjective ton?

This is a classic pronunciation rule that learners sometimes forget. Even though opinion is feminine, it starts with a vowel. To avoid the clunky sound of two vowels crashing into each other (like in ta opinion), French swaps in the masculine ton to make it flow smoothly. The same thing happens with feminine words like amie becoming mon amie.

Can I use other pronouns here to say 'it seems to him' or 'it seems to us'?

Yes, you can use any indirect object pronoun in this structure. You could say Il lui semble que for it seems to him/her that, or Il nous semble que for it seems to us that. As long as there is a specific person experiencing the feeling, the phrase expresses a strongly held belief and continues to use the indicative mood.