Problem setting currentTime in Chrome

Question

I'd like to be able to step forwards and backwards through an Ogg/Theora video by incrementing currentTime with code like this:

videoEl.currentTime = videoEl.currentTime + DELTA;

This works well in Firefox, but in Chrome the display of a new 'frame' is erratic, sometimes with a resolution of less than a second.

Is there any way around this, or is this just a fact of life for Ogg/Theora rendering in Chrome?

I'm using Chrome 4.0 on Windows XP SP3.