Don't use the slider. On the map you have a Red Dot that represents your current location. Put the mouse over the dot, click and drag it to where you want it to be.
If you have an easily identifiable location, switch to Satellite View, Zoom in and align.
With dozens of laps, zoom in on the section, and manually drag the dot from line to line to properly sync it up.
If you have the template loaded you can see the information update on the left hand side as you move the dot from line to line to line.
Generally speaking, if I do laps in the park I will always note the time (clock), distance and timer and use that data to help me align. Especially if I opt to turn on the camera in the middle of doing laps.
How is this supposed to work if you have say 30 lines overlaying each other within an area of say a few pixels at max zoom? It is fully random what gets selected when you click into this mess.
Sorry for the late reply. I missed the notification. If this is still relevant to you, this is what I do.
I on occasion have video of laps that I do in the park. The more laps the bigger of a pain the whole damn thing is. Alignment is always a PITA. As such, there are a few things I've instituted in my recording of footage.
When I start the camera (GoPro now, used to be a Contour Roam) I always notate the the Time of Day, time on the Garmin unit and the mileage. This helps me tremendously.
When I go to to align the GPX data I aim for an approximate location then switch back to the main screen. I have a Time of Day Gauge Hr/Min/Sec and it's easy to spot by how many seconds off I am from when the video begins. It's been a huge help.
As to the alignment of the data, especially when you have many lines going over each other what I try to do is measure how many seconds off I am from where I need to be. From there, I zoom in on the map to the max and look over the GPS lines. On most occasions, there will be areas on the map when there is a greater separation between the lines. I will use those sections to attempt to align the red dot and slide it backward/forward on the proper line (where it's not so cluttered) and look at the timeline beneath the map to see how many seconds I've moved it.
In your case, if you can find any one small section where the line with the red dot has some separation from the other lines, just play the clip for a second or two (or how much you can get away with) and then pause, slide the red dot forward/backward then go back to the video clip, rewind, rinse and repeat.
Granted, my lines are on a 3 mile circuit, if it's smaller, I'd wager it'd be a bit more difficult to do.
I hope my info wasn't too confusing. Let me know if any of this makes sense.
