Verify your game cache in steam is step one.
"Binkw32.dll should never be installed in your windows or system directories, if you copied it there, delete it, and Verify your game cache again.
LAST RESORT FOLLOWS, NOT RECOMMENDED;
If you still have an issue, move fnv4gb.exe and fnv4gb_helper.dll to the New Vegas install directory, run it once to create the exes folder. Select and COPY all the dll's in the New Vegas install directory to the exes folder."
I found this on nexus forums. Can't post links yet, but this is the entire post. It was posted by the mod author. Hope this helps out.