I just installed a clean fresh version of Joomla 3.1.1. I have made NO other additions/uploads/changes to the site other than to upload and activate AllVideos 4.5.0 from the AllVideos website using the Joomla 3 download option, and finally write an article and place the required plugin (only) in the article. The result can be seen here. godboggled.com/gr5/
As you can see all that appears on the page is 2 unsuccessful instances of the plugin. This is the first time in a couple years I have had any problem with the AllVideos extension, but it it the first time I have used these 2 particular versions together.
The Website tells me to not bother asking for help as I am using the "free" version of Allvideos.  In a nutshell, these two apps do not play friendly for me and there is NO DOCUMENTATION apparently to address this issue. I can't possibly be the first with this prob can I?

Are you absolutely positive that the plugin is enabled?
You could PM me access to your backend to check it out more thoroughly.

Pretty sure... but I sent you all the details to check ...  thank you.

As you can see now, the plugin works just fine.
Your problem was that you had copy/pasted the urls from somewhere else and had taken lots of junk styles which cut the tags in several places. To make sure nothing like that will ever happen, paste the copied text/url as plain text or through notepad.

Yiota, THANK YOU!!!!!!!!!!!!!!!!!!!!
Can't believe it was that simple. In the past I always cut and pasted straight from the youtube address bar. Never again, without a text editor to strip the junk, it seems.
Again, sincere thanks.
Beres