I sendt this video to all my friends.

Because you say "they all cried", I assume you mean this as something that has already been done.

If you say "I send this to all my friends", it is something you do continuously or repeatedly (you send it to your friends every day, for example).

If you say "I sent this to all my friends", it is something you did in the past.

I am not sure which you meant!

Yes, it is one of the best videos you must need to watch.

You could say "Yes, it is one of the best videos you need to watch."

or you could say "Yes, it is one of the best videos you must watch."

But after watch foring it more than 10 times.

"After watching it" is used because it suggests it is something you did repeatedly (more than ten times)

We also leave out the "for" here. You can say "more than 10 times", or you could say "over 10 times".

Nothing about speechthe content of the speech conten, that was excellent.

Here, we would say "the content of the speech" instead of "speech content".

Because you already mentioned the content of the speech, you do not need to repeat it. You can replace it with "that" instead, which sounds more natural.

We are in the year 2020 and this video was created atin 1940!

We would say we are "in" the year of 2020, or it was created "in" 1940. I also added 'and' to make the sentences fow together more naturally.

The black and white movie always has a “cool factor” power.

Saying "“cool factor” power" doesn't make much sense. We could say "a cool factor", but it doesn't sound very natural.

Some suggestions:
- The black and white movie is always very cool/so cool.
- The black and white movie always looks very cool.
- The black and white movie always look very powerful.

If this speech was spokingen by some presidents.

"spoken" is the past participle of 'speak'!

I think it willould be less attractive.

We say 'would' here instead of 'will', because it is hypothetical. Because we say "IF this speech was spoken...", we say "would".