For videos you don't necessarily need a strobe. You should WB the t2i when you get to 40'. I use a white card but anything white at depth will do. I have dual ike 161s "movie strobes" which as far as video lights go are not worth the cost. Don't get me wrong, they are great photo strobes, but just aren't powerful enough to consider using a full time movie strobes when you compare to white balancing (let alone use only one). You 'll get much better color with a proper white balance and you won't get that uneven coloring that presents when you have the subject lit, vs when they are just out of the light and not in any way color balanced. This is very much a question that there is no definite answer as opinions vary, but I personally would always shoot large fish at that depth with a custom WB vs strobes.
