First, use the [ c o d e ] and [ / c o d e ] BBcode tags to make your code more readable.
Secondly, you didn't proxy the requests through tor. You just started the service, but didn't connect to it.
Also, don't use os.system if you don't have to. There are better ways to do this:
As you're already using python, I'd suggest the stem library (
https://stem.torproject.org/)
It's a python controller library for tor, so it allows, for example, changing the identity. That way you don't have to restart the tor service everytime to get a new identity. Furthermore it makes your code more portable (should work on windows too).
FYI, the requests library doesn't support SOCKS proxies (wich tor is using), so you'll have to look for another http library that does support SOCKS proxies. httplib2 supports these kind of proxies if you have the pysocks/socksipy library installed (pysocks is the more recent fork, socksipy isn't actively developed anymore).
As for the code in general, using a for-loop would make it look cleaner (matter of taste). Assinging the content of the yourtube url to the variable "res" is unneccessary, as you do not use the variable later on.