Possible cause and solution to the problem:
Is the video too long?
Twitter maximum file length is 2:20, two minutes and twenty seconds.
Is the file too large?
Twitter maximum file size
Size: 512MB
Maximum resolution:
Resolution: 1920 x 1200 or vice versa
Format: MP4 in H264 format
Working file sample:
Format: MPEG-4
Format: AVC
Bit rate : 2000 kb/s
Width: 1920 pixels
Height: 1080 pixels
Audio
Format : AAC LC
Bit rate : 192 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 29 FPS
File size 200 MB
