Divx and Xvid sometimes will work in editing programs then later on it stops working.
Most of the time if you use it it will run slow, crash the program or just show a black screen.
I've made an amv completly with divx clips in the past and it was a pain >_<
Your best choice is to use an loosless codec for your clips.
so.??
To get your clips to work you need to re-encode them in a program like virtualdub and use a codec like Huffyuv or Lagarith
Its best to encode only the clips you need insted of whole episodes since those codecs can make HUGE files
you can download virtual dub here
http://prdownloads.sourceforge.net/virt ??? p?download
Since you are using downloaded episodes at some point you may get files in MKV or OGM format. For those you will need virtualdub mod to convert them
http://virtualdubmod.sourceforge.net/
I used these screenshots to show someone how to convert dvd vobs but they can be used here for this.
The screenshots are from virtualdub mod but what you are doing can be done in regular virtual dub
run virtualdub mod (or virtualdub) and open the video file wherever it is on your hard drive
After it opens go to "video" then select "compression" and select a codec like Huffy
You can use the buttons like shown below to select scenes you want to encode.
Once you select a scene go to "file" then save it as an avi.
Thats basically what you have to do! ^_^
*drinks sake*