As a precursor to the likely GX1 hack here's some information regarding the Panasonic GX1.

[More to come...]

The DMC-GX1 employs full HD 1,920 x 1,080 videos in AVCHD (MPEG-4 / H.264) format. The AVCHD format features almost twice the recording time in HD quality than the conventional Motion JPEG. The AVCDH matrix for i and p frames in 1080i is the same as each other (as seen in the attached file GX1 picture parameter set). Notably, the 720p matrices differ from each other from i frames to p frames (notice both pps matrices attached below)

Video AVCHD:

NTSC [Full HD] 1,920 x 1,080, 60i (sensor output is 30p) (FSH: 17 Mbps) [HD] 1,280 x 720, 60p (sensor output is 30p) (SH: 17 Mbps)

PAL [Full HD] 1,920 x 1,080, 50i (sensor output is 25p) (FSH: 17 Mbps) [HD] 1,280 x 720, 50p (sensor output is 25p) (SH: 17 Mbps)

Video MP4:

The DMC-GX1 can record videos in MP4 format. This format is suitable for editing videos on a computer or uploading those to websites. Resolution can be selected among 1,920 x 1,080 (20Mbps), 1,280 x 720 (10Mbps), and 640 x 480 (4Mbps), all at 30p (NTSC) / 25p (PAL). The mp4 mode records files to the DCIM folder. See attached 1080 p25 mp4 header info and streameye graphic for GOP and progressive confirmation.

The usual mini HDMI Type C. Video: Auto / 1080i / 720p / 480p (576p in PAL system)

Optional accessory (essential): Live View Finder (field sequential color, 1,440,000-dot equivalent).

More info on video capabilities: http://panasonic.net/avc/lumix/systemcamera/gms/gx1/video.html#avchd

Firmware: http://panasonic.jp/support/global/cs/dsc/download/fts/dl/gx1.html