http://mpgtx.sourceforge.net/
Suppose you want to split matrix-trailer.mpg into 166 playable chunks with the basename mychunk
mpgtx -166 matrix-trailer.mpg -b mychunk
Now processing Chunk 1/166 ... 100.00%
Now processing Chunk 2/166 ... 92.79%
[...]
You will then have 166 files named mychunk-001.mpg to mychunk-166.mpg