Cool video, but this is not new news, we have known about this forever. Also, it is best not to tie knots in Dyneema slings for a number of reasons.
I have received video material from some friends and experienced climbing instructors, showing some fairly alarming results concerning the use of knotted dyneema. http://vimeo.com/41522053
I apologize for the fact that commentary is in Swedish. Iīve uploaded two doodles to try and explain whats going on.
The results, in short, show that under heavy but entirely realistic loads (ff 2 with new rope and and test dummy), a new dyneema sling fails completely. This happens when the dyneema is shortened using two techniques which, at least in Scandinavia, are common and taught by instructors.
Any thoughts? To me the results imply that we should avoid knotting dyneema altogether, and use this fantastic material only in full length, stitched slings (like quick draws). At least until we know more about which nylon/dyneema/widths/knots combinations work and which donīt.