I'm about 99% sure those slomo sequences in that LF piece were shot with a Panasonic HVX200 @ 720 60p. 60 true progresssive frames per second lend themselves a lot better to slow/stop motion then 60 interlaced (60i) frames (30fps) like the Sony you mention.
The other issue is the format the Sony records to, HDV. HDV is a high compression format that uses a method where an "I" frame is recorded followed by 15 "GOP" (group of pictures) frames. The I frame contains full image information and the following 15 frames only contain information about the changes from the last I frame. Obviously for static shots this doesn't stress the codec but when you shoot high motion or pan the cam quickly the ability of the codec to accurately record the image properly get's stressed. HDV is also a 4:2:0 color based codec so color isn't sampled as well as Panasonic's DVCPro HD (4:2:2) or even DV which is 4:1:1.
Does this mean an HDV cam is incapable of good fast action video? Not really, in fact I've seen some good HDV based action video lately so I've just ordered a Canon HV10 which I'm going to experiment with.
I looked at Sony but opted for the Canon for the following reasons:
Image stablization: Canon uses optical, sony uses electronic. All reports say the Canon's is way more effective.
AutoFocus: The Canon has instant focus and a good focus assist mode, the sony's is conventional and they removed the focus assist the HC1 had. Focus is critical with HD whether manual or auto is used.
Sensor: the Canon uses a CMOS sensor and features a full 1920 X 1080 grid which literally provide resolution on par with their XL H1 (I know it sounds impossible but it's true). The Sony is using a high degree of builtin contrast and sharpening to achieve their final image.
Exposure: Neither cam provides true full manual control but the Canon at least allows separate control over shutter and aperture.
Biggest downside to the Canon is no audio inputs (which I don't care about) and no HDMI out. However the Canon has 3 channel component out which I've found provides equal quality to HDMI. The Sony appears to be better in low light, another feature that doesn't matter to me.
I saw that slo mo feature on the sony but if the HDV codec is limited to 25 mbs and is pushed at 30 fps how is it going to record accurately at 4 times that? I guess I'd have to see the video to make a call on that. Plus 3 seconds isn't enough to do anything with. (You can't record normally and then switch in real time to the slomo mode and back)
I have not been a big fan of HDV but the thought of replacing 8K worth of HVX200 with a $1000 unit makes it worth a try even if there are compromises and work arounds.
Anyhow here's some great reviews on both the Sony and the Canon and a link to some demo footage Canon has posted from the HV10.
iMovie will edit HDV but you need a lot of storage and a fast processor because it doesn't do it natively like FCP.
links: http://www.camcorderinfo.com/content/Sony-HDR-HC3-Camcorder-Review.htm http://www.camcorderinfo.com/content/Canon-HV10-Camcorder-Review.htm http://usa.canon.com/app/html/See_The_Difference/hd_cmos.shtml