Thumbnails in list_folder

Hey guys! new to the API so sorry for stupid questions... I'm wondering if I can do something. first off, here's my folder structure:

>HD Content

   >011_Blue

     >001_randombluename.mp4

     >002_randombluename.mp4

   >012_Green

     >001_randomgreenname.mp4

     >002_randomgreenname.mp4

   >013_Red

     >001_randomredname.mp4

     >002_randomredname.mp4

so it possible to do an HTTP request to get all the folder information using list_folder from the "HD Content" folder and pull the thumbnail of the first file in each of those folders? hope that makes sense. thanks for the help!