The bitrate might be different between those two videos. I've noticed differences between different sites in video bitrate - and even in the video codec used for the FLV container, when I download them to my PC.
Yeah, try an older video (like the lego beer song) and see if that plays ok. Seems all the new videos are in HD. Or better yet just use http://keepvid.com/ to download the videos right to your device and watch in tcpmp.
