How do I bring my Quicktime DV from 2013 to life? Back in 2012/2013 I've imported a stack of home video tapes from my DV camera into iMovie. I also converted a lot of files created by earlier versions of iMovie, some of them dating back as far as 2003 or thereabouts.

For as much as 2 years I haven't touched iMovie or those files. What I did do was update my OSX and all my apps along with it, including iMovie. I'm now on El Capitan (wish I Kept Yosemite) and my iMovie cannot read the iMovie files dating from 2012/13. 

Any thoughts? Tools?
Apple fully rewrote iMovie in version 10.x. For iMovie 2014 to open projects of iMovie versions 7.x, 8.x, and 9.x (iMovie '08, '09, '11) you have to use iMovie's 'update' feature which changes previous project files into the new format. To do that, you place the old folders named 'iMovie Projects' and 'iMovie Events' into your current 'Movies' folder. More details here:  https://support.apple.com/en-us/HT202853

For even older iMovie project formats ('iMovie HD') one would have to use  import them in iMovie '11 first (File > Import > iMovie HD Project) to bring them into that format, then 'update' the imported projects in iMovie 2014. However, when importing these very old formats into iMovie '11, they get stripped of added audio files, transition effects and titles.