Tente remover ^ e /:
RewriteRule cam1 http://admin:[email protected]/cgi/mjpg/mjpg.cgi [P,L]
RewriteRule cam1 http://192.168.99.130/cgi/mjpg/mjpg.cgi [E=Authorization:Basic\ YWRtaW46YWRtaW4=,P,L]
RewriteRule cam1 http://192.168.99.130/cgi/mjpg/mjpg.cgi [E=HTTP_USERID:admin,E=HTTP_PASSWORD:admin,P,L]
Por favor, me diga se funciona.