As most people are aware Adobe has stopped support for Flash on 64bit, no one knows for how long. Do not use the 64bit flash beta, it has major security problems.
Adobe Labs - Downloads: Flash Player 10 for 64-bit Linux
We have temporarily closed the Labs program of Flash Player 10 for 64-bit Linux, as we are making significant architectural changes to the 64-bit Linux Flash Player and additional security enhancements. We are fully committed to bringing native 64-bit Flash Player for the