It did provide a huge boost for music videos, since it screened them day and night; previously they'd mostly been confined to shows like Top of the Pops. It also provided a boost to British music, since people here were more used to making the videos than they were in the states, or so I'm told. And yes, it's true that these days cinema films are edited much more busily than in the past - jump cuts every five seconds rather than 30 (you'll have to look up the exact statistics) - and this is almost certainly the influence of MTV and of people who've grown up watching it and are accustomed to swifter editing.