Why can't I send a video?
Everything you send with Threema is encrypted before sending. This can require a high processor load, especially on older devices. We strive to provide both security and performance to all our users independently of their devices, which is why the sending of videos is currently possible within the following limits:
Android: Irrespective of its duration, the video's file size cannot exceed 50 MB. If you are using Android 4.3 or higher, you can compress videos in Threema > Settings > Media, allowing you to send even very large files, depending on the compression type.
iOS: Videos in high quality can be up to three minutes long; in low quality, videos can be up to 15 minutes long.