hey, mine came back.
did you re-install your OS or something?
that's what i did. basically, i installed a new SSD drive and manually migrated everything over after a fresh install, but i downloaded the latest OS combo update.
but at some point in the process (after i posted here), that functionality came back, but i'm not sure what triggered it.
from what i can remember, i moved my entire itunes database back over along with all the plists, preferences, etc.
also, i re-activated my quicktime 7 pro on my new machine. not sure which of those things made it work, because i did a lot of stuff to get my new boot volume back to the same state it was.
(i chose to do this instead of migration assistant because i wanted to do some house cleaning and not move everything over..it's kind of tedious because you have to move all kinds of secondary files over).
but i think the problem lies with QT, QT 7 pro or itunes, since that would be what is handling that play functionality more so than just the icon views...
let me know how/when your problem first started, maybe we can figure this out...because somehow mine is working again.