I too am struggling to get this working.
I am building CEF 3.3029.1619 using VS2015 and Windows 10
When I visit
http://www.igloovision.com using cefclient the introductory video is not played and in console.log I see
[0607/102030.398:ERROR:process_win.cc(140)] Unable to terminate process: Access is denied. (0x5)
[0607/102036.716:ERROR:render_media_log.cc(30)] MediaEvent: MEDIA_ERROR_LOG_ENTRY {"error":"FFmpegDemuxer: open context failed"}
[0607/102036.717:ERROR:render_media_log.cc(30)] MediaEvent: PIPELINE_ERROR demuxer: could not open
My own application gives the same render_media_log errors and then generates a fatal error
FATAL:elementanimations.cpp(109)] Check failed: *m_baseComputedStyle == *computedStyle.
I set the gn_defines environment variable to is_official_build=true proprietary_codecs=true ffmpeg_branding=Chrome.
Then I reran cmake and then rebuilt CEF but it makes no difference.
I also tried setting the gn_defines environment variable to is_official_build=true proprietary_codecs=true ffmpeg_branding="Chrome" but that didn't work either.
Thanks for any help