I dug into this problem a bit and inspected what's going on behind the scenes but ultimately the reason seems to be that discord internally generates a proxy_url to prevent IP grabbing and the embeded video that you see in the channel comes from the proxy_url.
If you inspect the embed that discord generates when you paste a link, it is not a rich embed, but a video embed. You can actually create this video embed yourself but likely due to security reasons you cannot send it without it getting mangled.
Inspected object:
{'type': 'video',
'url': 'https://example.com/video.mp4',
'video': {'height': 480,
'proxy_url': 'https://images-ext-1.discordapp.net/external/Tr36h2z0bxXh1JF-DYH6igRBj9SClhe_b1sxIF8CvgA/https://example.com/video.mp4',
'url': 'https://example.com/video.mp4',
'width': 480}}
How to create a custom video embed:
TestVideoEmbed = {}
TestVideoEmbed['type'] = 'video'
TestVideoEmbed['url'] = 'https://example.com/video.mp4'
VideoDict = {}
VideoDict['height'] = 480
VideoDict['proxy_url'] = 'https://images-ext-1.discordapp.net/external/Tr36h2z0bxXh1JF-DYH6igRBj9SClhe_b1sxIF8CvgA/https://example.com/video.mp4'
VideoDict['url'] = 'https://example.com/video.mp4'
VideoDict['width'] = 480
TestVideoEmbed['video'] = VideoDict
CreatedEmbed = discord.embeds.Embed.from_dict(TestVideoEmbed)
Despite the fact that you can create the video embed yourself, if you send it, somewhere along the line the discord api will turn it into a rich embed which lacks the proper fields and turns into this:
{'type': 'rich',
'url': 'https://example.com/video.mp4'}
Ultimately, the 2 limiting factors are that we would need to be able to create the proxy_url through the api and have the final video embed be sent to the client software as a video embed without being converted.
