I have a major issue with Picross for SNES changing resolutions and it fucks up my merging in AVIDub. Does MeGUI let you MKVfy multiple Avis in one avs files? That way I can hard set all the Picross Vol 1 Avis into one resolute files (512x488) as it switches from 256x224 to 512 x 488 and back constantly.

Ok that's great.
Select AVIWriter then check Resize Video and input the recommended resolution: 256 x 224. Also check Pad otherwise there will be a resolution change. Finally press ok and select the Lagarith Lossless Codec to start the rerecording process.
Hope it helps. Cheers!

I used Bizhawk.

One more thing: what emulator do you used to record that game?

yes you can do it Roja Calor. All you have to do is put the AviSynth script right next to the AVI videos and then in the AviSynth script input the commands like this:

AVISource ( "avifile1.avi" )+\
AVISource ( "avifile2.avi" )+\
.... etc.

Make sure the PointResize in the AviSynth must be like this:
(width*2,height*2) # Double-sizes the video (320x200 -> 640x400)

The recommended resolution for SNES games is: 256x224 >> 512x448.
Recommended emulator: Bizhawk.

I did it and it works! Cheers!
BTW if you need help PM me or get in the IRC for more details.