1. Have you tried to select an option such as "Convert captured images in software" -> "YV12 formats" or "YUY2 formats"? (CTRL+P -> General)
What rendering mode are you using? (CTRL+P -> Video -> Video rendering -> Rendering mode)
2. It's not BSplayer fault, but flash splitter/decoder. Unfortunately
AFAIK there's only one codec/splitter that uses DShow and thus can be used by BSplayer to decode flash videos, and this works only with some flash files and not with others