For those who are upset or angry at not being chosen, keep in mind that there were a very large number of applications so the fact that someone else got it and you didn't could be as a result of a number of different things.
Post-count and forum sign-up date is not relevant, but having posted lots of meaningful and intelligent ideas would certainly tend to get you noticed, so when your name comes up it will be viewed favourably. Being known for lots of OT spamming in the GD forums will do exactly the inverse.
There may be people with specific hardware that no one else has. This makes them good candidates to broaden the scope of stability testing. Better hardware isn't always a plus...there is a need to know the performance on lower end and older rigs too.
Previous experience is definitely a plus.
And when all of that's said and done, there are still often more suitable applicants than there are spaces. We can't have 20,000 betas if there isn't the internal staff to review the bug reports, confirm them and correct them, so...
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