Revised on Nov 20, 2013: Apparently `sub_frame` for `
googleaps.com` is required for comments.
Recipe for
https://www.youtube.com *only* (if you want youtube to be enabled globally, you need something else), with comments enabled:
list%0A%09%09xmlhttprequest%20googleapis
le.com%0A%09%09xmlhttprequest%20googlevi deo.com%0A%09blacklist%0A%09%09object%20 *%0A%09%09sub_frame%20*%0A%09%09*%20*%0A
Go to "Rule manager", paste in "Recipe" box, click decode, click import. Imported rules are temporary (as of now), don't forget to padlock them if you like the result.