YouTube views can be bought as Facebook fans or Twitter Followers. Of course, low cost bought views are from bots.
Some advertisers or agencies may be tempted to buy YouTube views for launching viral videos. If the bought views have good quality - i.e., viral video addicts - it may sometime favor the seeding phase of the campaign.
If the videos promoted by views buying are of good quality, it can also influence YouTube algorithm and gain better visibility in YouTube recommended video lists.
If it is low cost views (probably bots), the only effect is to display a respectable number of video views and to possibly avoid a shame number for a poor viral video. Low cost bought views have no effect on viral dessimination.
We may think that sometimes agencies buy Youtube views wihtout referring to their customer to avoid apparent too poor results for viral video.