First you have to be able to download youtube video as an .FLV file using the Mozilla addon for firefox (Video Downloader or Download helper).
You may have to rename the download file from filename.htm to filename.flv
You should also download a flash video player to play the file to make sure its ok.
http://www.martijndevisser.com/blog/...player-updated
Once you have the file run winmenc or memcoder or what ever encoder you want to use.
(iriverter is one of the most simple encoders to use but has limited options it is good to learn to use this one and then learn to use more advance encoders later)
http://iriverter.sourceforge.net/
You need to input the file by loading or drag and drop the filename.flv file into the encoder.
You then change the options:
Video Codec=divx or Xvid
Video Bitrate kbps=300 or less (set equal to original video rate)
Video Size=320x240
Video Frames fps=20 or less
(extra tab under video filers)
Video Filter:rotate=1
Audio Codec=mp3
Audio Bitrate kbps=64
Video bit rate should be about 300kbits or equal to the original bit rate shown under info or properties when playing with the flash video player. (no point wasting file size by encoding at 300kbits when the original file is only 100kbits, also youtube uses 64kbit for audio so dont go higher than this) you should set rotate=1 (rotate right) in video filter options if available.
You should also setup the output folder you want to save the new files to.
These should be all the setting you need to adjust ,you can now press encode to start encoding.
Once you have the finished file avi play it on your PC to make sure it works
(I use Divx player) it will be side ways if the rotate=1 was used.
If you look at the properties it should show what you entered above, if the setting are not the same you may have some wrong options set and will need to do it again.
If setting match above then you can copy the avi file to you miniplayer movie folder and watch it.
Never encode using higher bit rates than the original files video and audio bit rates.
you can not add information that doesnt exist. its ok to use lower rates as this creates smaller files for the miniplayer but also lower quality, but for a small screen may not be a problem. Youtube videos are usually low quality due to the high compression they use.
The same applies to any video format you want to encode (avi,mpg,mov,dvd,etc)
hope this helps ,any question just ask, I also knew nothing about encoding when I got the miniplayer, but using google to search for articles and reading the forums, and just playing with the encoding software, I soon worked out how to do it, dont be afraid to play with the encoder software ,the worst that happens is you end up with a file that wont play on miniplayer , just delete it and try again with different settings.