Indeed it seems your settings should be sufficient. Exactly how large are your video files?
Possible you can give me login to your panel so I can diagnose myself? I once experienced a server who allowed changing php ini settings, but the settings were just superficial and didn't actually have any effect.
Also, just curious why you don't consider hosting your videos for example at Vimeo? Vimeo/Youtube offer several advantages that your self-hosted videos can't compete with:
- Stream videos in multiple formats to support all devices.
- Stream videos in multiple bitrates to support slow and fast connections.
- Stream videos in multiple resolutions.
- True streaming (in contrast to play-while-downloading).