SEGA Japan has updated their Sonic Free Riders official site with a MUCH higher quality version of the games Tokyo Game Show trailer, which was originally revealed on their USTREAM account. Now you can view it without the blurry mess and get a better look at the game in motion. View it in widescreen at YouTube or the games website at the below link.
Source: Japanese official Sonic Free Riders website
Thanks to Woun at the SSMB for the YouTube conversion.