Why do i have to De-Interlace NX5U avchd footage?

[Faymus Media]

if i dont select "always" de-interlace in premiere pro cs4, the footage gets choppy...

i have the .mts file from a 1080p 24p sony nx5u....but its "native" 24p so it doesnt interlace, so i should not have to de-interlace right?

thanks for help..

 

[Faymus Media]

here is some RAW files from a NX5U....can someone edit the file give it "film" effects and see if you can make it smooth...or an explanation...

i dont want to buy this camera if everything is choppy....it seems every video online is choppy, vimeo.com or youtube.com

thanks