I run a digital publishing company and the best move we ever made was going from CDROM and DVD over to digital download. There are many realities you need to be aware of
1) Most file sharing is done by people who would NEVER buy your product, even if it cost 1p. These guys just love downloading and sharing stuff, most of it never even gets read or viewed. These are NOT lost sales - don't believe the ridiculous stats bandied about by the entertainment industry.
2) Only a very small proportion of pirated downloads will be from people who 'may' have bought your product had there not been the pirated version.The majority of your customers are good genuine people, never forget that - they appreciate the value of your work and are happy to pay, especially as they know it will hopefully lead to you producing more great products
3) A lot of people download pirated copies simply because it's more convenient and instant than dealing with shipped DVDs, region coding, DRM, incompatibilities, scratched discs etc.
4) There is nothing you can do to stop your products being pirated. It takes a few seconds to set up a rip of a DVD, and then the rip carries on in the background, no effort at all and uploaded within minutes. If you think sticking with DVD somehow is saving you from piracy, you really are kidding yourself! The fact that your stuff isn't out there already is simply because you have customers who are not interested in pirating it.
The solution is, learn from the pirates. Make it more convenient to buy your products - that means instant digital delivery, in a nice open video format that your customer can open in any device, be it computer, phone, iPad, dvd player etc. Forget about DRM and other 'locking' services, that just makes it a nightmare for your genuine customers, and does nothing to stop piracy (DRM is easily cracked). And as digital delivery has no material or shipping costs, you can make your videos cheaper for all your customers. Plus there's no VAT on digital delivery to customers outside the EU.
Remember, the large majority of file sharing downloads are not lost sales. These people would NEVER buy your products so it's pointless worrying about them. Sure it galls to know people are downloading your hard work for free, but I found it's best to get over that, there's nothing you can do about it, so just concentrate on making great products for your customers that they can easily and quickly buy. Then watch the money roll in
Seriously, going completely digital was a great move for us - we've made (and continue to make) much more money than we ever did with DVD and other physical formats, and have a lot less shipping issues (most of our customers are in the US, so it was a complete nightmare with lots of stuff going missing). Customers love the instant access and they can come back and re-download whenever they feel like. And if we ever need to update a product, then we simply update the master file on our site and send a quick email to our customers letting know they can download the latest copy from our site.
I'd also point out that all 250+ of our products are all available to download on thousands of forums, file sharing sites, torrents, cyberlockers etc and have been for several years. Yes, we must have lost out on some sales, but the fact that our business continues to grow with increasing profits each year tells us we have nothing to fear from file sharing.