Your PR1.3 upgrade might be incomplete (the file size mismatch means that you're trying to run the PR1.3 version of the app against the Flash shipped with PR1.2). Another sideeffect of this is that you might see green lines in some videos that worked fine previously.
On the forums many users seem to have been able to solve this by reinstalling the flash plugin (as root from the console)
apt-get install adobe-flashplayer --reinstall

works fine on my phone, wont install properly on a friends freshly flashed pr1.3, errors were encountered while processing: var/cache/apt/archives/ wrt-experimental wrt-api-experemental libwrt1
anyone know why?