The discussion on British Blades has really degenerated off topic. Somewhere on this site there is a thread where OldJimbo posts links to the movies in question.
British Red has put it very clearly. That is all the test proves.
The reason for filming it was to prove to people that a cheap stick tang was strong enough to take abuse, let alone what bushcraft usually calls for. There have been, and still are, many people who go on about how a knife needs to be about 4mm thick, with a full, untapered, tang, in order to be strong enough for real use. I think I read one guy saying he wouldn't even drill holes to lighten a 4mm thick full tang because it would weaken it. That test with a cheap little Kellam stick tang was meant to give the lie to those concerns. I think it proves its point rather well.
As for why Mors suggests the technique, well, I can think of two reasons. The first is that he uses that technique to fell quite large trees in Canada, not from choice of course, but it is possible. Mors commented at the Moot last year that the wood we get here is different from that he is used to, both in hardness and in BTU, so it might be hard to reproduce his results in the UK. The other reason I can think of for Mors using that as a test is that he knows that surprisingly small knives, like the little Mora, are capable of serious work. How do you prove to someone raised with things like Ka-bar combat knives, that this dinky little Mora is tough enough? Well, Mors knows that its tough enough, and hammering it into a tree is a way of demonstrating it to people who are skeptical.
