Make sure the character set is explicit on the server.

utf-8 is the standard and most used:

AddDefaultCharset utf-8 
AddCharset utf-8 .html .css .js .xml .json .rss .atom

Make sure audio/video works by defining the MIME type on the server:

AddType video/ogg .ogv
AddType video/mp4 .mp4
AddType video/webm .webm