Hello,
I have a lof of experience in PHP and HTML5 applications, but not with video, however, please check PMB for a link to a simple html5 video playback I set up for you.
Your project's main challenge is the security of the site. This includes the payment, the user data and the videos.
The first two, I can solve no problems as I did many projects that required a high level of security. Videos I don't know how to fully protect, yet. Streaming them from a PHP file should work, though. ..Yes, I would code the server side in PHP, but I don't think it would have a huge performance hit on your servers as there will be pretty basic stuff done with the DB. Unless you also need sorting, filtering and 'bubbling' (personalized suggestions) each user on your site. Another problem would be copy protection. I don't think html5 has this implemented in all browsers, but i recently heard that netflix is trying out html5 so probably html5 DRM protection is coming to all modern browsers soon.
I'm only a programmer so my bid does not include design, but I will code the UI in Bootstrap so theming should be easy as pi:)
For the music part, do you require 30 seconds snippets created by the server or will you (or content owner) upload these?
The same question for videos, but with different file formats and resolutions (to save bandwidth)..
I can't tell you a final price as I don't know what backend/server side features you need, but my bid includes all the work that needs done in PHP/HTML5+JS: UI, admin, content owner admin, stats, CC integration, everything, exept installing a streaming server (if its required - my demo does not require it, but then again the content in the demo does not have DRM...)