Snippets from Encoding Procedures:
http://tasvideos.org/EmulatorResources/MakingAVI/Common/Windows.html
-------
# FFDshow: Download and install. During installation, install all components. For "select supported video codecs", make sure to select H.264. The rest of the options should be left to the default.
# Configuring FFDshow to capture: After installing, go to the start menu > ffdshow. Select VFW codec configuration. Under the encoding tab, select H.264 lossless. Under FOURCC, select H264. Other settings can be left on default. Select the Decoder tab now, and click Codecs in the left hand list. A new menu should now appear. Find H.264 in the list and make sure it is set to libavcodec by clicking on it in the decoder column.
(This only has to be done the first time.)
----------
Create initial h.264 lossless capture.
In the case of emulator specific settings, check the Emulator Settings - Windows article for help.
1. Run the emulator and load the ROM.
2. Increase the emulation speed to about 400% (the command to do this varies by emulator but often it is the '=' key). This will speed up this initial encode by making the limiting factor your cpu.
3. Turn off frame display. Configure sound (This varies by platform, but typically it is the highest setting in the emulator, 48khz stereo, or 44.1khz stereo. In the case of NES it is 48khz mono). Pause the emulator and load the movie file.
4. Select the Record AVI option. Select the mencoder folder to save the AVI (or whatever workspace folder you like). Call it capture.avi and save. Select FFDshow in the dropdown box. Click ok.
5. Unpause emulation. Record until the ending and one loop of the ending song if there is one that loops. Don't worry if you record a little extra afterward as you can clean it up with mencoder in the next step.
(This varies slightly for each emulator.)
--------
After you get this largely oversized Raw encode, I suggest opening the video with the program Virtualdub, trimming off any extra content with the home, end, and delete buttons. Direct Stream copy implies no compression, Full Processing mode implies compression.
Audio: Compression: MPEG Layer-3
Video: Compression: x264
This should be good enough for youtube.