According to Mythbusters it certainly works against RPGs... IF you can make the shot lol
The problem I have is, even if the shot hit, in the video the round had already left the barrel. Assuming it was an HE/HEAT round it detonated outside the barrel... It probably would've had some nasty effects on the barrel and maybe crippled the main gun if the guy with the pistol was lucky... but completely trashing the tank? Please... that frontal armor
might get scratched by a direct impact HE round and is known to defeat damn near everything else thrown at the
front of the tank. An indirect explosion like that would have the gunner asking wtf? And then splattering the guy with the Co-ax.
If it was a SABOT round... there would have been no explosion at all.
Aside from that and killing a jet with a single burst from an UMP .45. Great show. Good music, good camera work. 8/10 from me, personally I think it would have been cooler to have him dodging the co-ax from the Abrams, sliding under the tank and walking out the back with a detonator and clicking off a block of C-4.