I ran in to this issue a long while ago... the trick is this... you need to set the Expires headers and kill the eTags... that will make flash load the flv from cache...
proof
http://www.digitalbarn.tv/work.htmlif you watch the net you'll see that even thou it's streamed on the http it only calls it once...
if your on apache use the .htaccess file.. add
# 3months
pdf|swf|mo
v|mp3|wmv|
ppt)$">
Header set Cache-Control "max-age=7257600"
# WEEK
Header set Cache-Control "max-age=604800"
# 45 MIN
Header set Cache-Control "max-age=2700"
# CMSMS unset ETag
ng|gif|js|
css|gz|swf
)$">
Header unset ETag
FileETag None
you can read more here
http://developer.yahoo.com/performance/rules.html#expiresthis will solve your issue
cheers
jeremyBass