Both video adverts and traditional banners can be a lot more expensive on that, depending on the situation. In my line of work, for example, I never see banners for less than $0.003/view, and $0.02/video advert is considered cheap.
As to whether advertising can cover streaming costs - yes it can, certainly when it comes to gaming content.
Display ads (google ads, for instance) average about .05 cents per view ( ie- you need 1k views to get 50 cents )
A server that comes with 100TB of bandwidth is about 200 bucks a month.
Now, is it going to be profitable? That all depends on the quality settings of the video + length + bitrate, etc..