I've been on 8.04 LTS since April of 2008, I use it all day every day at
work and have never had any problem viewing flash content. It all "just
works" by default.

if you are having problems, make sure they are not self inflicted.

1. Adobe flash is included in the "ubuntu restricted extras" bundle. If
you installed flash by hand, please undo what you did, and install Adobe
flash using the package manager. If you have not installed the ubuntu
restricted extras bundle, that's what you need to do.

2. Make sure that adobe flash is the only flash player installed, as
installing multiple competing flash players will cause problems
including an inability to view flash content. Remove any competing
players e.g. gnash, swfdec, etc.