The market is saturated, however depending on what you are teaching you could create a segment for yourself.
Are you teaching a "style" vs breaking down a particular song? If you are teaching a style, then you probably come off better with a series of videos or just a cd/dvd compilation. If you are breaking down a song, you may have some luck with getting people to pay a premium for a single song, but it really depends on the song. You also have to balance the complexity.
if the song is very complex, and your breakdown is difficult to understand or follow, you will lose people. if the song is too simple, many people may already know how to play it and therefore won't buy anyway.
I like the way HNS Music and PianoClubHouse do their videos. They give you like a minute or 2 breakdown preview for free. If you like what you see then you pay for the full breakdown video.
Jlewis