I think that You rather do something work during installation and/*or* tweaking it afterwards. First of all, "it doesn't work" isn't enough. You need to check for kernel messages - execute 'dmesg' from terminal as root, *after* You try to record 720p video, and post it here. Remember, that dmesg isn't real-time updated, it is "snapshot" of messages up to point of dmesg execution.

In case of errors indicating, that voltage is too low for Your MPU and overclocked DSP combo, try disabling vdd1 and vdd2 (I hope You're using latest power kernel - kp49 - cause trying to get 720p without it would be time waste). Also, get sure that You're using 'dsp' overclock profile for 'debugging', not Your custom one - it makes things easier for analysis.

If that doesn't help, please provide us more details.

/Estel