As far as I know it got pulled due to instability. Although beta 1 was pretty stable (with the advantage of being more compatible with PulseAudio), beta 2 of Flash uses a lot of CPU and causes crashes with many common websites.
As for the crashes with beta 2 of Flash, it is actually a bug in Firefox's "windowless mode" support and not Flash itself. The issue is already fixed in upstream Firefox and is being tracked on Launchpad bug #239182. Resolving the windowless mode crashes won't help the high CPU usage, though.
John,
As far as I know it got pulled due to instability. Although beta 1 was pretty stable (with the advantage of being more compatible with PulseAudio), beta 2 of Flash uses a lot of CPU and causes crashes with many common websites.
As for the crashes with beta 2 of Flash, it is actually a bug in Firefox's "windowless mode" support and not Flash itself. The issue is already fixed in upstream Firefox and is being tracked on Launchpad bug #239182. Resolving the windowless mode crashes won't help the high CPU usage, though.