I'm making an app where a video should automatically be displayed when I enter a letter and for some reason the video sometimes plays automatically and sometimes doesn't.
Look in the Video Player blocks for the event that fires after completion of playing something.
That can be used instead of that second Clock component.
You would also have to supplement the event with a global list PlayList of video files waiting to be played.
Start with that list empty.
When a new letter is detected, look up in a table what file to play. (You could also rename all your .mp4 files to match a JOIN (letter).mp4 for simplicity). Add the new file name to PlayList, then check the length of list of PlayList. If there is just 1 item, that means no other file is playing, so you can start playing item 1. Otherwise, you are done.
When the Video Player event fires to signal end of play, remove item 1 from PlayList. If Playlist is an empty list, you are done, else start playing the new item 1.