Describe what actually stopped
Windows 11 distinguishes screen-off timers from sleep and hibernate timeouts. Energy saver and power mode add further behavior. A dark display alone does not tell you which state occurred.
Observe whether audio continues, whether a normal input wakes the picture and whether the session resumes where expected. These observations are more useful than calling every interruption a player crash.
Review the relevant timer
Microsoft places screen and sleep choices under Settings, System, Power and battery, Screen, sleep and hibernate timeouts. Inspect the plugged-in and battery arrangement actually used for viewing. A laptop moved off its charger may follow a different policy.
Adjust only the timer needed for the intended session and keep a reasonable normal-use configuration. Do not disable all power behavior merely because one display timeout was inconvenient.
Check the next ordinary action
Repeat a short viewing interval under the selected power arrangement. Confirm that the display stays usable and that the computer still wakes and resumes normally afterwards. If the app alone closes, investigate that separate behavior.
When seeking help, include power source, timeout setting and whether audio continued. This establishes the observed state without claiming that a timer change fixes every playback interruption.
Questions answered
Is screen-off the same as sleep?
No. Windows exposes separate timers and states.
Why does the problem happen only on battery?
Inspect the battery-specific policy and Energy saver state before assuming the video source changed.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.