Since September have there been any updates in which apps or readers can play eBooks in the epub format that can play embedded video and audio? Or is iBooks and the iPad the only device? Has Android created a comparable app yet? Also has there been any sort of fix to the issue of exporting to epub from indesign 5.5 and the selected poster image for videos disappear when in use on the ipad?
The only person I know who writes about this is Liz Castro in her blog. She has posted nothing new in the past few months about new readers that support video. The eReaders which do are iBooks (iPad and iPhone) and the Color Nook.
You can read more about it by getting Liz's eBook on including video and audio:
There has been no change to the way poster images are exported in InDesign CS5.5. You still have to edit it in the EPUB file manually to make it appear. I expect we will have to wait for CS6 for that to change.