Playing through VLC instead of mpv, and knowing where you got to.

mpv carries a Lua script laev writes on every launch: it saves the position every five seconds, counts the seconds actually watched as against seeked past, and appends the day's total to the log the heatmap is drawn from. VLC has no equivalent — scripts there are installed into the application, not handed to it at launch — but it does have a web interface, and that reports the playhead. So laev starts VLC with that interface bound to localhost on a random port behind a random password, and polls it on the same five-second cadence the Lua script uses, writing the same three files by the same rules.

Which means everything downstream carries on working unchanged — resume, Up Next, the watched ticks, the stats, the heatmap, MyAnimeList scrobbling — because all of it reads those files and none of it knows which player wrote them.

Two things don't come across, both of them mpv scripts rather than playback: skipping intros, and the stinger prompt. laev says so when you switch.