Advertising exists before videos. And during videos. And if you're not fast enough, after videos. But it exists, and may the executive who came up with the idea burn in eternal torment.
That said, sometimes you have to watch an ad before a video. But how much ad are you willing to watch before you say, "YouTube, go f*** yourself, this isn't worth it"? What is the proper "Ad to Content" ratio?
It sure as hell isn't 30 seconds for a minute and a half trailer. Why am I being forced to watch a commercial before I watch a commercial? Why, it's because some jackass in an Armani suit can jingle some more change in his pockets!
GO TO HELL, YOUTUBE. YOU HEAR ME?! I'M NOT WATCHING A 30 SECOND COMMERCIAL FOR 90 SECONDS OF ENTERTAINMENT THAT IS ALSO A COMMERCIAL.