Found this Canon C100 (http://shop.texasmediasystems.com/Canon-C100-Cinema-EOS-Camera-6340B002_p_4993.html) test on vimeo:

Canon C100 Test AVCHD vs ProRes on Vimeo

If I'm being honest, the difference is negligible to my eye but that may just be the result of Vimeo compression.

If it was anything like the FS100, the AVC-HD looks almost identical unless you have a lot of detail in movement - which is where the ProRes compression wins. But looking at a vectorscope, there's a lot of quantisation (rounding up) in the colour information. Invisible to the human eye on the first generation material, but take it beyond 5 generations (i.e. into the broadcast world which can be up to 10 generations to the consumer endpoint) and that invisible quantisation soon gets 'fugly' (technical term).

But in the case of the C100, which I see as being significant IF my eyes don't deceive me, is there not a lot of aliasing on the internal recording (0:47) which seems noticeably absent on the external recording? (thinking about the big blowups of your eyes).

Hope you're feeling better - though you could have claimed it was a reenactment of a couple of scenes from The Machinist! :-D

To the guy who uploaded the video (if he sees this):

There's clearly something wrong in the video. The AVCHD not blown up shows clear jaggies in all the hair on the guys face. It doesn't even have to be blown up to see really nasty jaggies. There's something off here with how this AVCHD was handled in your NLE. I've never seen AVCHD that looks like that at normal size. I would see what the issue is and re-upload this video before more people get the wrong idea about the C100's internal picture. It looks like you have the AVCHD in an interlaced profile. I know for a fact you used Premiere because it can cause issues like this if you have a fields setting setup wrong. Not knocking you too hard I hope, just don't want people getting the wrong idea from what they see. No footage should blow up that way either and hold the jaggies it originally had (which shouldn't be there). Anything blown up to that degree should be softer and it's clearly not in the case of the AVCHD.