There is a new folder in the “io.casper.android” folder called “Video Thumbnails”.
You can add 100×100 PNGs into it called “username.png” (replacing username with your Snapchat username) and when you set a video as a story this PNG icon will be set as the thumbnail shown in Snapchat and Casper.
Unfortunately it won’t work for photo snaps. You can add one icon into the Video Thumbnails folder for each Snapchat account you have.
For example, if you have two accounts, “abc123″ and “123abc” you would add two icons called “abc123.png” and “123abc.png”.
If you are logged into the account “abc123″, when you send a video snap, the abc123.png file will be uploaded and used as the video’s thumbnail.