There is a nice, lightweight JavaScript Flash Detection Library, which is smaller and more convenient than using SWFObject. You should consider it, if you only want to check if Flash is installed, what version of Flash Player is installed etc., but you're using different method of playing FLV
movies.
SWFObject should be considered only, if you're also using it for playing Flash movies. For just checking, if Flash is installed or what version of Flash player is installed, it is to heavy, in my opinion.