Well
Code:
/dev/sda1 /media/sda1 vfat defaults 0 0
will not give you "Read and Write" permission in vfat partition as local user.. so the parameter(s) I prefer
Code:
/dev/sda1 /media/sda1 vfat users,rw,umask=000 0 0
Source
As for disabling/enabling multimedia contents in browser (Firefox) in concerned
Edit> Preference> Content