Does phase detection auto focus really makes big difference?

I want to buy dslr both for video and photos, i like nikon d5200 and sony a58, nikon has better image quality and big range of lenses, while sony has phase af which is great for videos and countinues focus. If that does not make difference in real world than nikon is better suited to me…

You will find the Sony more useful for video, but if video is just an occasional thing you would do better with the Nikon.

You can however give a Sony the same, or better, image quality as Nikon by getting it an expensive lens. Either a Sony "G" one of the Carl Zeiss optics, or a premium Sigma, Tamron or Tokina.

See this site: Scores of more than 4.25 indicate a good lenns.
http://www.dyxum.com/lenses/results.asp

Phase detection on DSLRs is faster are more relaible than Contrast detection; some now have hybrid sensors.

Though.

Yes the autofocus works on SLT"s just as any DSLR would outside of video.
BUT the next question is, are the lenses optimized for video. Many cheaper sony lenses come with SAM, This is build in the lens and is the cheaper version, it also makes a bit of sound. THIS will be recorded unless you use an external microphone. Sure SAM is a step better then in body screw drive focussing but not that much better.

The better sony/zeiss lenses have SSM. Those are quite silent indeed and you shouldn't notice them on the audio track of the video. Again though using an external microphone tends to mean better audio.

And then there's manual zoom. Not every lens is as optimal such though. Many SAM lenses [the cheaper ones] have such a small focussing ring and such a small throw [how far round the focussing ring goes] that manual focussing is not perfect.

The kitlens on the A58 for instance that. Isn't as nice to manual focus with. Of course manual focussing makes no sound but you still need a good throw and a decent grippy focus ring.

I got some tamron's that are more expensive, driven autofocus wise by the screw drive so rather loud on video. But manual focussing a dream, big focus ring and long throw so smooth.

So YES an SLT is great for AF during video. But. It better is an HSM[sigma] or SSM[Sony] lens to keep the sound of the autofocus down. SAM? Not silent. Screw type in body focus? You'll hear it.

For video you need a good lens, not just in image quality but also in the ability to manual focus and. If you desire autofocus without making allot of sound.
As ever DSLR"s are not made specifically for video so their inbuild microphones aren't that great. Buying a microphone, no matter if you buy canon, sony, nikon, pentax, etc. Will improve audio quality.
But please. Be warned for the loud lenses.