The TX-7 uses the AVCHD encoding for its 1080i videos.
The TX-5 only captures at 720p. What encoding does it use? Not the AVCHD, I believe, or it would be advertised as such.
At the end of the day, is the TX-5 video bigger or smaller than the TX-7 video? (720p is inherently smaller, but the encoder is less efficient.)