what's on the glass on my tank?

The worms are probably planarians, not harmful, and good live fishfood as you've found out... but you also don't want an excess of them. Cut down on feeding and increase water changes. I don't know how they got there, have you introduced any new plants lately? Here's more reading on them:
http://www.taursys.com/kasha/JAS/Articles/PLANAR.htm

I believe otos like softer brown (diatom) algae but I have heard other people say their otos eat green algae, too. The green algae spots may be too "hard" for them, though. Yes, scrape it off (an old credit card works well). You may find that after scraping, the swimming fish may eat some up as its floating around, before the filter gets it.

those white worms are common in my 20 gallon grow out because of exessive feedings. Over feeding and not enough water changes as previously mentioned are the cause of this.

The only turbellarians that bother us are the few we can see!. The ones in the gravel aren't so conspicuous as the ones on the glass. And the microturbellaria-- the majority of flatworms are too small to see-- are a mainstay of the processes of recycling detritus. Part of the natural ecology that gets established in the tank.

Their lifespan is short. That's why flatworms populations are "boom and bust." Reducing feed has an effect within days.