I'm compiling using fcsh compile from Simon Gregory's AS3 bundle which is great but I'm not sure how to open the SWF in Flashplayer without choosing the Build command.
Try the 'Run' command ( R ). Use the bundle editor to change it's behaviour, by default it will check for a custom launch.sh script, when one's not found it tries to open deploy/index.html. There are alternatives commented out that should be pretty self explanatory.
Cheers, Simon