There are some other apps and solutions out there but if someone wants a special-purpose smartapp, here you go: GitHub - greglarious/BlinkMotionHandler: SmartThings app for integrating with blink camera motion alerts
Basic setup is to have IFTTT trigger a Simulated Switch in smartthings
This app uses that switch to trigger a Simulated Motion Sensor and a real switch
After a config num minutes it turns off the real switch and sets the Simulated Motion Sensor to inactive.
End result: when the back door camera detects motion, it turns on the back door light for 5 minutes and also triggers a motion detector which can lead to further automation. After 5 minutes, the Simulated Switch and the real switch are set to off and the Simulated Motion Detector is reset.