We have a client who is having issues viewing longer (25-40 minute) h.264/.mp4 files on both their Macs and PCs. The video plays properly for about 4 minutes then stops playing completely or the audio stops. My understanding is they are using QT Player and Sony Catalyst Browse. They get the same issue when attempting to upload to Brightcove. All files play correctly on our systems and upload properly to our YouTube channel.
Videos are encoded from the timeline in h.264, 1080, 12 Mbps, VBR 2-pass, AAC Audio @ 320 kbps