I made some test movies with mednafen 0.8.A
http://mednafen.sourceforge.net/
Bloody Wolf (USA cartridge)
Bonk III (USA CD)
Akumajou Chi no Rondo (JAP CD)
download
Play them and see if they sync. I don't know any of these games. I picked them because they were mentioned here.
It seems there's no way to record from power on, only from savestate. If you loadstate during recording, it doesn't re-record and it doesn't stop either--instead I think it inserts the savestate into the movie, loads it, and keeps recording. This makes a really big movie file and looks awful so I didn't use them.
There's no GUI and no error messages, so here's some preemptive troubleshooting.
Run a (optionally zipped) cart with:
mednafen "rom path/rom name.pce"
mednafen "rom path/rom name.zip"
To run CD games, first specify a (optionally zipped) v3.0 CD bios in mednafen.cfg:
pce.cdbios rom path/rom name.pce
pce.cdbios rom path/rom name.zip
Run a CD with:
mednafen -loadcd pce "rom path/rom name.cue"
Cues must not refer to anything besides iso, bin, wav.
Put the movie files in the mcm folder, match the name with your rom, load the rom and hit shift+F7 to play back.
Some personal config prefs:
Exclude md5 from save filenames:
dfmd5 0
Make your bram/sram saves compatible with other emulators:
filesys.disablesavegz 1
Display 256x240 games (most of them) in the authentic aspect ratio:
pce.xscale 2.4
pce.yscale 3
or some integral multiple of 0.8:1
For 342x240 games, use a 1.06875:1 multiple.
(There have already been some forum complaints about this.)
Overscan (full) display:
pce.slstart 0
pce.slend 239
Plain old scaling:
pce.videoip 0
pce.special none