Added stray frames

[Kredithaichen]

Depending on the overall duration, the generated video has often a few frames of another snippet appended at the very end, creating a very jarring cutoff effect. Maybe there is a way to pad the video with an extra second or two if the concatenated snippets don't fit exactly the script length?

[harry0703]

This seems to have a bug, I will fix it as soon as possible. Could you please upload the final video (final.mp4), and the video script (script.json) here for review? Thank you.