As the price bracket increases so does the expectation for more features and greater control over video making, though this won't be realised in every purchase.
Despite the Pentax K-5 being the most expensive of the cameras on test in this price bracket, it's the only camera that doesn't offer any autofocus ability for its movie mode. While, arguably, some of the other cameras' autofocus modes aren't of pratical use, and therefore obsolete, this is certainly an area Pentax needs to see some progression in. The AVI files are good quality, but the file sizes are huge and this just isn't going to cut it for more pro-grade applications either.
The other two remaining DSLRs - the Nikon D5100 and Canon 600D - are very similar on paper and have some great features, but are quite different beasts.
The vari-angle screens of both cameras are very practical for movie shooting and the 3.5mm mic jack of each model means external microphones can be connected for sound recording. The D5100's continuous autofocus is a step in the right direction, but it's not fast enough to deal with all subjects and the video files are a little 'choppy' rather than 'cinematic' in playback.
Although the Canon 600D's files may look the better of the pair, its single autofocus system is no better than that found in the Canon EOS 1100D, which mis-focuses by such a margin that it's next to useless (this could explain why Pentax avoids implementing such a system in the K-5).
Then things step up a notch.
The E-PL3's movie capture abilities are great, there's full manual control and the continuous autofocus is fantastic too. The letdown is in the final quality however, which lacks the sharpness and clarity of its peers due to over-processing. But still a very strong effort that's a breeze to use.
The Sony Alpha A55 also puts in a sterling effort. Its continuous autofocus is very, very fast and equally as accurate, which allows for swift focusing between a variety of subjects. However the A55's main autofocus strength is also its main 'weakness' in other regards: as the camera can only autofocus to the centre-point of the screen there's a lack of control; no single autofocus features; nor are there manual controls. But it is the cheapest one of the bunch here, and for that it's a grand performer that's far faster than anything else out there.
At the top of the tree is Panasonic's G3. For the snap-happy consumer crowd this camera has (almost) everything you could need. Final quality is great, the touchscreen is fantastic for changing focus points during capture (something the Olympus E-P3 failed to address), the continuous autofocus is very smooth as is the ability to track moving subjects. I
t may not be quite as swift as the Sony A55, its 2.5mm mic jack is annoying and there's no full manual control. But what you do get, however, is a device that's small, affordable, endlessly useable and will appeal to the wider masses that want good video capture and controls right at their fingertips.