Video is corrupting when compiled with mxmlc but not Flash IDE

Question

I have movie clips containing FLV video sequences.

When this FLV plays in a SWF compiled from mxmlc, the video is completely corrupted - all different coloured blocks. If I compile from the IDE the video plays fine.

It's a bit more involved than this:

• If I play multiple copies of the same FLV at the same time, they're fine, whereas if I play various FLVs at the same time, they corrupt.
• They don't always corrupt on every playthrough - it's not consistent.
• If I zoom into the corrupted video, or move the player window, the corrupted image remains intact, i.e. it's not like a screen redrawing error where the corrupted area will often change or clear.

Does anyone know of any Flex compiler options, or SWC authoring strategies to get around this?