When scrolling while watching a flash video the flash widget thingy becomes solid grey. After bringing another window to the front, overlaying the flash widget area, and switching back to Epiphany the video re-appears. I guess I'm triggering a area-damaged-event or somesuch there I've tested this with Epiphany 2.28.0 and WebKitGTK 1.1.5.1 and .2
I cannot reproduce this issue and it was filed quite a long time ago. I'm going to close it for now. If you have a test case which demonstrates this issue with a recent version of WebKitGTK+, please feel free to re-open it. Thanks for reporting!