that's easy to fix:
go to plugins/content/jw_allvideos and locate jw_allvideos_sources.php.
there you find the following code:
// YouTube
"youtube" => "
<span style=\"width:{VWIDTH}px;height:{VHEIGHT}px;\" class=\"allvideos_player\" title=\"JoomlaWorks AllVideos Player\">
<object type=\"application/x-shockwave-flash\" style=\"width:{VWIDTH}px;height:{VHEIGHT}px;\" data=\"
www.youtube.com/v/{AVSOURCE}&hl=en&fs=1\">
<param name=\"movie\" value=\"
www.youtube.com/v/{AVSOURCE}&hl=en&fs=1\" />
<param name=\"quality\" value=\"high\" />
<param name=\"wmode\" value=\"{TRANSPARENCY}\" />
<param name=\"bgcolor\" value=\"{BACKGROUND}\" />
</object>
</span>
replace it with:
// YouTube
"youtube" => "
<span style=\"width:{VWIDTH}px;height:{VHEIGHT}px;\" class=\"allvideos_player\" title=\"JoomlaWorks AllVideos Player\">
<object type=\"application/x-shockwave-flash\" style=\"width:{VWIDTH}px;height:{VHEIGHT}px;\" data=\"
www.youtube.com/v/{AVSOURCE}&hl=en&fs=1\">
<param name=\"movie\" value=\"
www.youtube.com/v/{AVSOURCE}&hl=en&fs=1\" />
<param name=\"allowFullScreen\" value=\"true\" />
<param name=\"quality\" value=\"high\" />
<param name=\"wmode\" value=\"{TRANSPARENCY}\" />
<param name=\"bgcolor\" value=\"{BACKGROUND}\" />
</object>
</span>