You are kinda lucky.
A friend of mine had an account at bet365 so I asked him to use my opera, log in there and try playing a live stream.
As it seems, all its live streams are in h264, thus they do not play in stock opera, and there is no fallback option for flash, thus having flash installed or not makes no difference. So all I have said at the other thread about opera's poor html5 support apply for your sites and distro as well.
Opera for Linux