BUR #5951 has been approved by @evazion.
remove implication video_with_sound -> video
remove implication flash_with_sound -> flash
category sound -> meta
create alias video_with_sound -> sound
create alias flash_with_sound -> sound
I imagine the main reason this doesn't already exist is because of the flash with sound tag. However, as support for uploading flash has been discontinued, it seems appropriate to create this alias. sound consistently sits on the upper half of Missed Searches, and I think video with sound is what people actually want 99.9% of the time. Even sound's wiki directs you exclusively to that tag.
sound is a pretty common search term on other websites, so I think this is a natural alias in accommodating that.
One possible alternate would be to remove the separation and alias flash with sound and video with sound together into a sound tag. You could then find the less common flash videos with a search of sound filetype:swf.