The first thing a filmmaker does when he/she has completed their film, is make a "screener" in order to:
1) secure a producers rep/agency to help sell the film
2) secure a foreign sales agent
3) sell the film directly to a distribution company
4) send a copy to investors
5) send a copy to KICKSTARTER supporters
For years these "screeners" were standard definition DVDs, and over the past few years - BluRays have become more common - but filmmakers almost always have to create BOTH DVDs and BLURAYs. The disadvantages of disc screeners are obvious - you need to pay for shipping and it takes time for the physical screener to get across the country, or out of the country. DVD-Rs, and BD-Rs are notorious for skipping and stuttering on some players and computers. Not to mention you have no way to control where the disc ends up after the person you shipped it to screens it. And you have no way of knowing if he/she even watched it, or when they watched it.
Last year during TIFF and AFM, I saw an increased number of folks using password protected links on VIMEO instead of disc. Recently, I discovered INDEE.TV - which is a simple, cloud platform for delivering screeners. Pricing is very in-expensive and even offers a pay-per-use option for $5. Which is faster, and cheaper than you can fed ex a DVD or BluRay - with much more security and functionality. You can also pay $35/mo for a fully customized screener page.