That sounds like a horrible mess. Presenting users with "Would you like to give this site access to UDP?" is not a question most users can answer to any level of competency. Developers dream, users nightmare.
WebGL has been a good example of the difficulties you face when offering low level access- buggy graphics drivers could result in an all-out crash.
Your proposed solution and criticism thereof presume that there is only one way to delegate trust to a web app and that it should entail that the user understand UDP.
WebGL has been a good example of the difficulties you face when offering low level access- buggy graphics drivers could result in an all-out crash.