We've talked with the Chrome team and once 44 goes into production (out of beta) this functionality won't be hidden behind a flag - it'll be there for everyone to use!
We added a bunch of warning messages to the current app to make it so users knew that it didn't work. Right now we're just in the process of stripping all of those out.
Chromebooks for Intel should be very easy to support, so expect to see something in the next 3 weeks or so
Chromebook's running ARM might be a little trickier and in many cases won't be able to do a full video transcode (just because they aren't powerful enough) but we do plan on adding support here (and perhaps warning messages on the files that won't work). Still trying to figure ARM out
Hang in there guys, should be out soon!