I know ski tracks is generally regarded as innacurate and I agree, but it told me that I did 70 and I believe it from watching this video that my friend recorded of me going by. Im 200 pounds and was on 168 rental skis, but my tuck is very low and it was early morning perfect groomed and icy, which all contributed. This was at breck, I tucked from the top of the run, and this is near the bottom.
You have to tell us the camera and the lens setting, since with a gopro or those action cams, it has an extremely wide lens, giving a highly exaggerated sense of speed, either of the subject being filmed or the scenery. It is discussed a bit here under "Perceived Speed: Wide Angle":
I was told that I was going pretty slow on my video. To my defense, the camera was not facing forward, but toward me, thus the perception of movement is only in the objects in the background. Plus I had a camera with 25mm equiv lens, a gopro cam has a lens that has 3.3x the coverage, thus gives a much higher perceived speed. To verify, I viewed some gopro videos on utoob of some trails that I am familiar with and one was a flat passage trails where pretty much nobody even bother turning and the video looks like they are flying down, with the trees zooming by, etc.
As for your video, you skied too close to your friend, thus it is hard to judge how fast you were when you passed him, unless someone does a frame by frame analysis.