I don't have sound this week at home, so I'll have to pass on videos at the moment.
For me the transitions help a lot with bringing horse off-forehand IF done correctly. Especially trot - canter one. It's been a real challenge for my qh because of her build, and it takes lots of effort and time to make the transitions "clean". The worst one so far is trot - walk (lacking the impulsion sometime even with the leg on). Halt - trot and walk - trot seem to be the easiest ones. But, yeah, the transition should be clean.
If my walk - trot one doesn't go well I move horse back to walk and ask again (although I don't have to do it often now). Same with canter: if it goes off the bit, raising head, etc. I move her back to the nice balanced trot and ask again right away.