KakaoTalk's video limits
KakaoTalk accepts files up to 300 MB each on phones and PCs. Videos sent from the photo album are also re-compressed by KakaoTalk to a lower quality, while videos sent as a file keep the quality you chose here.
The preset aims at 291 MB so the file stays safely under the limit whatever unit the app uses.
Send it as a file, not from the album
Users report that sending from the album can show "over 300 MB" even after compressing, because the check uses the original in the gallery. Sending the downloaded MP4 with + › File uses the new size. On a PC, drag the MP4 into the chat window.
How much fits in 300 MB
300 MB is generous: about 14 minutes of 1080p at 2.8 Mbps, or 35 minutes of 720p at the Smallest level (sound included). For a shorter clip you can also pick Custom and aim lower, such as 50 MB, so it sends and downloads faster on mobile data.
Quality the recipient sees
A file-sent video plays at the resolution you chose. For viewing on phones, 720p or 1080p at the Balanced level looks clean; keep High quality for footage someone will watch on a TV.