Thanks for attention. Here is a discussion on how to merge videos from Spark in VLC. The detailed steps are as follows.

Step 1: Download and install VLC media player on PC. After installing, please run it and choose the "Media" option in the upper left corner;

Step 2:  Then, in the pop-up menu, please tap on "Open Multiple Files...". Under this interface, please touch "File" and then go to "Add" to add videos from your local files. (It can not support rearranging video files, so you need to add them as the order you want);

Step 3:  Now, go to "Play" and click on "Convert" in the drop-down menu to enter another interface, in which you need to choose the output directory and hit "Start". Please wait patiently. The merging process will take a moment.

Note: VLC only supports merging videos in the same format.

For beginners without any other requirements in merging videos, VLC is very suitable. If you think it can not satisfy you well, you can consider its alternative - Joyoshare Video Joiner. Such a tool supports merging videos in various format and if the videos are in the same format, it will not cause quality loss.

Thanks for the tip!

If you do care that VLC is a little complicated. I recommend you to use Joyoshare Video Joiner to combine videos. It can join videos in a lossless way and it is totally free if you  join videos no more than 5 times.