Who enforces 25MB: Gmail, Yahoo Mail and ProtonMail cap attachments at 25MB. Outlook is stricter at 20MB. Note that mail encoding inflates an attachment by roughly a third, so a 25MB file can be refused by a 25MB limit — target 18-20MB if the recipient is on a strict server.
What fits in 25MB: roughly 80 seconds of 1080p, three minutes of 720p, six 12MP photos, or a 300-page text PDF.
Worked example: a three-minute 1080p clip at 25MB works out to about 1.1 Mbps. Acceptable for a walkthrough or a recital; visibly compressed for sport or anything handheld.
Sending on chat rather than email? 16MB is the number you want — the hub explains why.