Philip Jägenstedt wrote:
Anything that can cause the element to switch back and forth between
displaying fallback and video is a no-go, that would cause a race
condition for if plugins/images in the fallback content. If they have
event handlers the results will get ugly fast:
<video>
<!-- network lag -->
<source>
<!-- network lag -->
<source>
<!-- network lag -->
<img src=foo onload="alert('how many times will you see this message?')">
</video>
The answer to the question in the alert is "once". This is true in the
current fallback model, and would presumably be true in the new fallback
model.
For the current model, note that all the text says is "should not show
this content to the user". While this is not defined anywhere, it
doesn't seem to indicate that the content's DOM should not exist, for
example. In Gecko, at least, the image in your example will be loaded
and hence its onload will fire.
-Boris
