I did a search on this and came up with nothing, so I hope I am not duplicating a thread already but I was wondering...

IYHO, what would be some mandatory trade organizations/associations to belong to if you wanted to build a business and a career as a videographer specialzing in outdoor and corporate videos? Are there even specialized organizations like that? or are there better, more general groups? What are the benefits these organizations provide?

Any insight would be greatly appreciated.

I've never heard of any national groups, there might be some local groups in your area but frankly, I've never heard of any groups locally either.
If you're looking for a group to join to network with, try the local Chamber of Commerce or other business groups that meet usually 1X a month for food and networking.

If you're looking for a group of other video folks in the same area of interest as you, well I guess you're back yo square one.
Sorry.

I'm not sure of your level of experience, equipment, or general knowledge. However, WEVA is from what I have seen, a wonderful place to start. WEVA is the Wedding Event Videographers Association, and can be found at www.weva.com .