Playing videos breaks after reloading pages in ESR 78-based builds
We set browser.privatebrowsing.forceMediaMemoryCache to true in
#33856 (closed). It turns out that this caused a
regression which
lead to videos breaking if one re-loads pages (see comment
3 for steps to
reproduce).
Lucklily, this is already fixed in Firefox 80 and the patches are small. We should backport them.
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