I have got a few Russian friends, who I communicate with in Russian. Many of them use the word youtube. I have noticed that some of them pronounce ютьюб and some - ютуб. I am not sure which one is correct so I use the English pronunciation т.е. ютьюб. Is there a rule on how to pronounce correctly? Thank you in advance!
On an everyday level, there's no right and wrong way. Ютьюб is more conventional and consistent with similar Russian phonetisations, which is why it's the one that would be used in broadcast media and anywhere else that "correctness" is required. Ютьюб is also, however, a bit of a disaster as far as euphony and ease of pronunciation are concerned. Still, as a ютуб person I think I'm slightly in the minority.
Youtube is a foreign proper name it should be pronounced according to the foreign language pronunciation rules. So, since
tube is pronounced as
[tju:b] this should sound like
ютьюб. And for any russian-speaking person who keeps an eye on his/her pronunciation, saying
ютуб means to show the ignorance. But there are cultural influence on that (slang, etc.). So
ютьюб is the correct way to pronounce this, but
ютуб is rather a slang form which may be widespread.