Consider these factors:
1. How high was the craft the last time you saw the video? Was it 380' due the RTH? If that's the case, it likely didn't hit anything before auto-landing initiated from a 10% battery level.
2. What direction was it travelling at 12%? It will likely continue traveling that same direction, it won't change directions since you had no control of it.
3. At 12% battery, you have about 1min left before it should auto land. It stops horizontal movement when auto land starts. It's likely unharmed in the field or a tree maybe.
4. Since you lost GPS signal, your logs will not show where it landed, it's likely way off, since it travel a distance without GPS signal. However, if the logs stopped recording GPS before it started flying away in one direction, you're screwed. This becomes even more difficult to estimate.
Trying calculating a search area using the log's last position and direction/speed. Note the battery level, and do your best to estimate the speed and direction it was going (based on logs last entry),. Continue to follow the path it was going from where last logged, in the same direction, for the length of time you expect it to travel before it reaches 10%, triggering auto land. Do this with Google maps, which lets you measure distance (as a crow flies) by right clicking any spot on the map.
IE. If the last log shows the craft was at X position at 18% headed due north, you would have about 2min left before reaching 10% (I think), in a typical flight mode (this is debatable, I know). So if it was doing 30mph (I think you mentioned top speed) during the last log entry, that's .5mi/min. With 2 minutes of flight left, that calculates to roughly 1mi from the last log. Look for the craft 1 mile due north of the last log of position X. Continue looking in the same path direction it was going. Searching with a drone would be helpful, since the craft is white, easy to see from the air, typically.
Hope this helps.
