Found while investigating a paragraph level issue in T100106#3277569 -- presence of an HTML "track" element in a "video" element triggers the check for "<tr" in BlockLevelPass::execute. This can cause a wikitext paragraph containing a video (in video.js mode, which doesn't use a wrapper div) to be treated as not needing "<p>...</p>" wrapped around it.

Result is that there is no line break between the two lines in an example like:

this is line one [[File:Folgers.ogv]] yay

this is line two [[File:Folgers.ogv]] yay

Inserting a \b into the regexes seems to resolve this.