Respawn's Vince Zampella has confirmed -- several times, in fact -- that you won't need to preorder a copy of Titanfall in order to get in on the upcoming beta.
Exactly what you need to do to be eligible for beta access hasn't been made clear as yet, but given Titanfall's reliance on EA's Origin service, having an Origin account is probably a good start.
Zampella also confirmed that unlike the recent multiplayer alpha stress test sent out to select players, there will be no restrictions on talking about the game, streaming footage to services such as Twitch or posting game footage on YouTube. In fact, as we get closer to the game's March release, Respawn would be sensible to encourage and highlight the work of YouTubers playing the beta and sharing their experiences, as this is becoming an increasingly important part of how people make a decision on whether or not to jump in to a new game -- particularly when it's the start of a new series.
Zampella previously said the beta would be available on Xbox One and PC -- no Xbox 360 version from the sounds of things -- but hasn't yet given any further details such as a date. However, the same leaked information that prompted Zampella to reveal the "super secret" platform details for the beta suggested that we could expect the first phase of beta testing to run between February 14 and 19, so it's plausible that some of you could be playing Titanfall as soon as a couple of weeks from now.
Titanfall itself is set for release on March 11. Let's hope it enjoys a significantly smoother ride than Battlefield 4!