Ok heres something.
I realised that this test - the Mamba one was done with blanking. So I repeated with no blanking and guess what I get similar results to you. Same scan speed and angle just red laser as the vid camera seemed to overecxpose the green making it difficult to see. First vid shows red scan complete then shows a close up.
second vid - and heres the thing shows the scope trace set to XY and it displays a similar shape to that being projected. This shows that the scanners cant track accurately with this input.
http://www.stanwax.plus.com/laser/rednoblank.wmv
http://www.stanwax.plus.com/laser/scope.wmv
The thing I find most interesting though - and maybe someone has an explanation for this - is that when I lower the scanspeed to 1000pps so the intermediate points are shown more clearly, the return seems to have as many points as the scanned line. I would have expected several points as the object is drawn with a quick return to the starting point without any intermediate points. I am guessing this is needed for better return accuracy but dont know.I expected the scope trace of YT to show a sawtooth wave but it in fact is a triangle wave.
Rob