Sand tigers are generally not aggressive unless provoked. They are common on the NC wrecks - especially the Papoose. Diving with Sand tigers is one of the big draws of NC diving. It is normal to see multiple sand tigers on one dive. They are generally docile although they have been known to harass spear fishers. Their appearance can be really threatening since you can see spo many teeth, but those teeth are nice pointy kind of rounded teeth that are designed to poke into fish - not to rip or tear. The one swimming towards you was not posturing. The "4th" most dangerous shark comment is typical media (probably tv) BS although I have never seen one that lists STs as dangerous. Their docile temperament paired with their scary appearance makes them very popular aquarium sharks. Please consider reading Peter Benchley's Shark Trouble for some good general info about sharks.
See the following links for sand tiger info:
http://www.colszoo.org/internal/drum_croaker/pdf/2004SS2.pdf#search="sandtiger posturing"
http://www.flmnh.ufl.edu/fish/Gallery/Descript/Sandtiger/Sandtiger.html
http://www.sharkinfo.ch/SI1_00e/ctaurus.html
http://www.elasmodiver.com/Sandtiger shark.htm
http://www.postmodern.com/~fi/sharkpics/ellis/sandtigr.htm
Some really cool video:
http://www.nautilusproductions.com/shark.html
Diving with Sand tigers:
http://members.aol.com/fpsndiver/fpsn11.html
BTW, nice video!
See the following links for sand tiger info:
http://www.colszoo.org/internal/drum_croaker/pdf/2004SS2.pdf#search="sandtiger posturing"
http://www.flmnh.ufl.edu/fish/Gallery/Descript/Sandtiger/Sandtiger.html
http://www.sharkinfo.ch/SI1_00e/ctaurus.html
http://www.elasmodiver.com/Sandtiger shark.htm
http://www.postmodern.com/~fi/sharkpics/ellis/sandtigr.htm
Some really cool video:
http://www.nautilusproductions.com/shark.html
Diving with Sand tigers:
http://members.aol.com/fpsndiver/fpsn11.html
BTW, nice video!