It is not worth the trouble, because you would have to disable digest to get the name of the files right. So the solution is to fix the library. In the case of Sound Manager 2, I did this:
Some CoffeeScript that I require:
#= require soundmanager2
jQuery ->
soundManager.swfNames =
"/soundmanager2.swf": "<%= asset_path('swf/soundmanager2.swf') %>"
"/soundmanager2_debug.swf": "<%= asset_path('swf/soundmanager2_debug.swf') %>"
"/soundmanager2_flash9.swf": "<%= asset_path('swf/soundmanager2_flash9.swf') %>"
"/soundmanager2_flash9_debug.swf": "<%= asset_path('swf/soundmanager2_flash9_debug.swf') %>"
soundManager.setup
debugMode: <% if Rails.env.development? %>true<% else %>false<% end %>
url: '/'
In my copy of soundmanager2.js (V2.97a.20130512), inside the definition of normalizeMovieURL
:
url = ... // After url is set
url = sm2.swfNames[url]; // Workaround