[Performance] Timing instrumentation for analysis; Re-use MP video player and other assets to address performance.
[Subtitles] support discovery of subtitles (as opposed to CC)
[Subtitles] more concrete recognition of subtitles and default subtitles
[Subtitles] Refactored initialization of video player view for showing/hiding CC button
[Subtitles] more complete UI w.r.t. recognition/detection of subtitles.