glad you got it worked out..
i have HTML5 video disabled on my computer so that "adobe flash player" is used instead, for watching videos at "youtube"..
here is an article about how to disable HTML5 video, if you want to:
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www.trishtech.com/2012/0 ··· firefox/here is all of the settings that i use, to try to disable HTML5 video-and other related things:
disable "loop.enabled" = "false" (disables FF's "hello" feature)
disable "media.autoplay.enabled" = "false"
disable "media.directshow.enabled" = "false"
disable "media.gmp-gmpopenh264.enabled" = "false"
disable "media.gmp-gmpopenh264.provider.enabled" = "false"
disable "media.gmp-provider.enabled" = "false"
disable "media.mediasource.enabled" = "false"
disable "media.mediasource.mp4.enabled" = "false"
disable "media.mediasource.webm.enabled" = "false" (already set to false)
disable "media.ogg.enabled" = "false" (trishtech.com)
disable "media.opus.enabled" = "false" (FF's "hello"?)
disable "media.peerconnection.enabled" = "false"
disable "media.wave.enabled" = "false" (trishtech.com)
disable "media.webm.enabled" = "false"
disable "media.windows-media-foundation.enabled" = "false" (trishtech.com)
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i am not sure about all of those settings..