Having seen reviews from other Optoma users I thought I'd give this a go.
Unfortunately the PM101 "Universal" mounting bracket doesn't live up to it's name!
Firstly, the mounting supports on the PM101 did not fit over the mounting points on my HD65. After having tightened all screws up, it did at least stay still, so not too much of a problem.
HOWEVER! The main problem was the bolts supplied. They were too long by quite some way, so I had to hacksaw them down to size!
My final gripe is that the PM101 is supposed to be adjustable. It certainly is for left/right movement, however I can only assume that up and down adjustment is only available for projectors that have the mounting points on the back. This would allow the supplied brackets with an elongated hole to be able to move up and down.
The only way I could adjust the bracket to point where I wanted was to put washers under the screw on the back mount to tilt the whole thing upwards.
In summary don't buy this if you own an Optoma HD65 Themescene unless you are a DIY enthusiast!