People have been talk which is the completely accessible media player for Drupal. Especially for the goverment agencies, fully accessible player is a must.
But it is always hard to make a media player completely accessible to keyboard and screen reader. Recently I found a module in our project that can meet the requirements from the AGIMO (Australian government information management office) standard. I thought it would be useful for anyone that is struggling loking for a accessible media player.
Nomensa Accessible Media Player module is a really simple module that turns all your media links into players. It is not a popular module, but it can really do the job.
Check the module page for the details.