Couldn't you make the same argument for images? I know some sites try to be tricky by disabling right-click, etc., but the same "rule" definitely still applies.
Or is it generally believed that images are of less "value" than video?
Yes of course; it's trivial to "steal" (ie copy to your hard drive) any image in a web page. The practice of disabling the right click is completely pointless, and just infuriates users - don't do it.
To get an image you don't even need to do anything vaguely hacky like Ctrl-U: you can just take a screenshot of your desktop. Pop open your favourite image editor and crop it: job done.
The best way to protect images on the web is to a) watermark them b) have them in low res.
But the general point is: if it renders to your screen it can be copied.
I think this is why corporations worried about "stealing" will still opt for Flash encrypted delivery vs HTML5-ey "friendly" delivery.
Any good player framework will likely account for this, hopefully by allowing all the same DOM-ey calls that one could perform with HTML5-ey video to be performed on flash through some sort of wrapper.
I don't think that content companies will just let it happen.
Or is it generally believed that images are of less "value" than video?