Just an addendum when I tried to create a new md5 with a more complicated rig and ran into problems.  I was again getting that mesh stretching, and again, the fix was adding in a “root” bone that all other bones parent to, deleting stray vertex groups, and making sure control bones in Blender had “Deform” unchecked (although I don’t think that last part matters).  I was able to do a reasonably complex rig and it’s loading ok.  Now to animate and make sure that works as well.

Flow is Blender->AssimpView->Flash.

Some tips:

- Always have a non-animated root bone.
- Two bones must not have the same name.
- Have as few weights per vertex as possible.
- Remove zero weights. They are still used in calculations and can result in broken meshes, when a maximum is exceeded.
- Keep your total bone count around 40 for each mesh, but always below 42 to get hardware skinning.
- (Currently) The maximum amount of vertex weights is used for all vertices, regardless of how many weights each individual vertex has. So, have 200 vertices with two weights and one with three and your skinning will always be calculated with three weights. Balance is the key - you rarely need more than two weights.

Best regards.