I have reverted back to the old version and everything is working fine - captcha, encoding of videos, etc.

I may not have your new features but at least I will have a functional site.

Have placed your upgrade on a developmental server which runs the old version just fine but chokes as already noted on your upgrade. Captcha fails preventing users from creating accounts. Have tried to re-upload captcha to no avail. Videos encode but fail to properly play or even launch.

So if the problem is local than you have provided no insights or support with how to rectify this situation. Again, this is only when doing the upgrade. Simply uploading the new files in to their respective directories and upgrading the mysql file with the update your provided.