Add /.*\.swf to your ad blocking black list. However, this will block all Flash. Personally, I find it easier to then disable ad blocking for sites where I want Flash to occur (e.g. YouTube) rather than to try and disable individual items of Flash on the go, so blocking all Flash works for me.
Hopefully, in OmniWeb 6 we'll have the option to block Flash (and other plug-ins) separately from ads.
Hopefully, in OmniWeb 6 we'll have the option to block Flash (and other plug-ins) separately from ads.