Unless the Rawl resin ampule was faulty, which I think is most unlikely, then it is very likely that the resin wasn't mixed properly.
I've never actually used the Rawl ampules but have used very many of the 10mm Spit Maxima ampules supplied by Petzl for their Collinox anchors. I've always fixed the anchors by hand but with twice as many twists than the 10 recommended by Petzl and have never had any fail the 6kN axial test.
I've never found them difficult to install, as Simon suggests, and most of the ones I have installed have been whilst hanging from a rope. Unless you were installing them upside down, which would be a bit of a faff whichever system was used, I can't think of an easier resin anchor system to install.
I've never been convinced that the drill powered mixing system in the video is better than doing it by hand.
It would be interesting to see a number of different anchor systems installed in a block of clear perspex to see exactly which method gives the best visible mix. Obviously testing is the only way to know its ultimate strength.
What type of anchor did you (al) install as this might have a bearing on the mixing?
It's a good job they were tested before being put into service.
Mark