It would really help if you provided a screenshot of your relevant blocks, so we can see what you are trying to do, and where the problem may be.
To get an image of your blocks, right click in the Blocks Editor and select "Download Blocks as Image". You might want to use an image editor to crop etc. if required. Then post it here in the community.
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.
To be honest I just tried getting the basic code running before integrating it into my app. So I opened a new project with the code.
I didnĀ“t change anything instead of the "file://".
I do find the the recorded video(s) in /storage/emulated/0/DCIM/100ANDRO/Name of Video.mp4
But I canĀ“t play any video after recording.
use Do it to debug your blocks, see also tip 4 here App Inventor: How to Learn | Pura Vida Apps
see also Live Development, Testing, and Debugging Tools
You might want to replace your local variables temporarily by global variables to be able to use Do it until you found the bug...
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by Taifun.
Thanks so far! I managed to find two files for each video, that was recorded:
/storage/emulated/0/DCIM/100ANDRO/Name of Video.mp4
Size: depending of lenght
/storage/emulated/0/Android/data/edu.mit.appinventor.aicompanion3/files/Name of Video.mp4
Size: always 9Byte and I canĀ“t open it manually
Theses errors occure:
Companion Screen:
The file seems to be in ASD.
Error: The player canĀ“t load the file in /storage/emulated/0/Android/data/edu.mit.appinventor.aicompanion3/files/Name of Video.mp4
IĀ“m not sure if this 9 Byte file is the right reference to open the Video, and I donĀ“t get why it is created.
as already said
the message "the variable is not bound in the current context" does not help very much in debugging...
the video player might expect a full path, which starts with file:///storage/emuated/0/Android/data... or a relative path, which is /Android/data/...
Taifun
hi there!
i am currently working on my project i.e based on emotion detector in which i need to send my audio file from mit app inventor to my machine learning model via mqtt and my mentor suggested me that use base64 for this it makes easy for me, my doubt is we are converting the audio file into string, right? it is encoding i want to send the string to my machine learning model as audio file, can you please help me with this. By the way, it's a great work i observe keenly.
I have not tried to send files by MQTT, the usual thing is to send small information.
Do you need to use MQTT? Can you use FireBase or CloudDB? What is your "machine learning model"? What is your MQTT Broker?
https://community.appinventor.mit.edu/t/esp32-mqtt-broker-publish-subscribe-thingspeak/10490
