Jiggimi, as you said, there is no way to use the flashplugin in Firefox on OpenBSD.
Minitube is a new option in OpenBSD as of 11July2010. It avoids multiple security issues with linux, xorg and flash that have not been addressed in OpenBSD 4.7
http://openports.se/www/minitube
Links to security vulnerabilities
http://www.invisiblethingslab.com/re...ry-attacks.pdf
http://www.linuxsecurity.com/content/view/153005?rdf