[e] (0) Try to elaborate on why the UA might pick particular media tracks
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=24895
Affected topics: Video and Audio

git-svn-id: http://svn.whatwg.org/webapps@8543 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit c12bc2d5c2688c554cfd28805dd98610238900d6)
(cherry picked from commit ea7c2c9f1f90d6cd3e3f7296ac15bff9000834ea)
[e] (0) Try to improve wording for track selection text.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=24895
Affected topics: Video and Audio

git-svn-id: http://svn.whatwg.org/webapps@8552 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit 21b53f5bc594524ed3a01c524750cbe64399d294)
(cherry picked from commit 0dc300922bb823aa5bb51c1d55e222da370227ca)