Just one kill? Couldnt u record a bit longer? The kill itself isnt suspicious for me, i heard the guy running myself and i would've done the same. Aimbot? Not from what i saw in the demo.
Now the suspicious part for me is how he knew that the guy would run from B to tunnels, since there were 3 of his mates running around him and he couldnt hear anything. I watched the demo 4 times and i couldnt hear him running there... U should have recorded a bit longer, at least a few more kills, to avoid this confusion.
Anyway thanks for the report, but i will wait for more opinions.
Cheers...