are the fiberglass 1 and 2 dvds right?

I ordered the Fiberglass I and II DVDs. I am watching them and on sub enclosures they just put a resin/talc mixture painted on the inside and leave it be. I have always been told to glass the inside for a stronger enclosure. The resin/talc mixture doesn't seem like it would be strong enough.

Also on one they just used reenforced body filler to strengthen the sub enclosure

...so who is right?

It all depends on what you wanna achieve. I have those 2 dvd's also, and learned a lot from them, but it's always a good idea to lay a few layers of mat for strength either on the inside or outside. Of course there are exceptions and other ways of doing things though. I know of people who make a thick mix with resin/talc/chopped mat, and paint it on the inside of kickpanles. It makes it solid, and for 4"-6" drivers it's perfect. If I were doing a sub enclosure though I would use multiple layers of mat for strength. As a general rule of thumb I like to use 12-15 oz of mat for a sub enclosure, and maybe 2-5 oz for kicks or pods. It's the fiberglass mat that gives an enclosure strength not the material. If you do an internet search you can find tests to where people compare different types of materials and their strengths when resined. It usually comes down to the same story though. The stretched material gives an enclosure shape, but the added mat/ reinforced filler gives strength. That's why a lot of people use Polydex material to build enclosures. It stretches easy all ways, doesn't sag, absorb too much resin (less money spent on wasted resin), and gives a smoother surface to apply mat over which means less sanding. These are some of the tips I've picked up along the way, and there's many different ways to do things though. Do some researching and see what works best for you.