only the current version of browsers are supported. specifically, firefox 3.x is not supported. deal with it.
firefox: if you get a security error involving localStorage (check your error console with ctrl+shift+j), go to about:config and enable dom.storage.enabled.
For youtube embedding / linkification, check out YouLink, which works on the entire web, not just 4chon.
for exhentai sauce, check out ExSauce.