iPhone sends small-blurry videos to contact

Almost every-time I send a video to a certain family member they say the video is super tiny and pixilated. They show me and it is! It’s being sent through IMessage but on their phone it shows a mini video thumbnail and when they click it, it is extremely pixilated. When I send it I never view it that way so I don’t know what’s happening. It’s super irritating because I’m trying to send important videos and they can’t even see what I’m trying to show. The video length usually never passes 2 mins. I looked online and it said it my settings might be on low quality image mode but it’s not. The other person also has an iPhone and we have the same phone provider so I really don’t know what’s wrong. Can someone please help?