Questions and discussion for this lecture live here. Fire away by hitting Reply below 
Hi, the direction of the member GC should be in tension, not compression, in the final solution.
Well spotted @TRISTAN_HO_YI_EN - thanks for flagging that.
For anyone else reading this - it was calculated correctly as a tensile force earlier in the solution, but I carelessly drew the arrows in the wrong orientation in the final sum-up at the end.
Seán