Why some AVI to MP4 converts produce shaky results?

[polaatx2]

Here's an example: http://blog.torkzadeh.com/dick_cheney_and_haliburtonmp4

I used to mediacoder to convert from an AVI original that is NOT shakey. The original was cut by Avidenux on windows.

Some other AVI conversions are much more shakey. Some others are not. Yet other AVI conversions have sound synch issues.

Is converting from AVI problematic and are them recommended settings?

[meRobs]

I suggest you try the settings given for MP4 in the Encoding Guide, listed under Tips & Guides.
Even if these settings are not exactly what you would like, they will at least serve as a starting point.