Sounds like streaming the video and scanning the file at the same time is more than your computer can handle.
As a test, try excluding your Music folder and see if the problem goes away. If it does, then this is your issue.
Since .m4v, .pdf, .epub, .ipa and .m4a files CAN be maliciously infected (even though I haven't seen an example yet in the wild), I'd caution against leaving the Music folder excluded long-term.
However, you may want to exclude the TV or Movies folder inside there and only perform manual scans when the contents change (I've got a script posted on these forums that allows you to do that -- it's for changes to the mail folder, but will work here too).
-
Andrew
Threat Researcher
SophosLabs
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