Converting .MTS files to .M4V

[MigranedMankey]

I have a sony vixi a hf r11. It uploads videos to my macbook pro in .mts files. I downloaded a program named handbrake to try to convert these files to .M4V files that play on iMovie. I followed some youtube instructions and thought i had finally converted my movie files to .m4v, but i still can't import them to iMovie. when i try importing them on iMovie they show up as .m4v files but i can't select them and their font isn't bold it's grey'd out(know what i mean?). I still try importing them on iMovie but it just freezes up my iMovie and i can't force quit. I'd really appreciate some help from someone who understands this dilemma, before i obliterate a fine piece of equipment.