If you want to add a video, the best way to do so is to upload it as a file. If it's a video that's hosted online (e.g. Youtube), there are tools online that specialize in downloading videos. A quality of 1080p or 720p is recommended (if those are not available, try to always go for the highest quality). Also, make sure that it's on an acceptable format, the most common being .mp4.
- In order to have both videos play back to back, you need to add a sequence. Click on the green plus (+) sign, scroll down to where you can see the orange options and select "Sequence" to add it to the list. You can now resize it however you want.
- Select this new Sequence. That is, in the list to the right, "Sequence" should be on a blue box (if you see a dotted orange square on the design you know it's now selected). Click on the green plus (+) sign once again and select "Video" to add it to the list. You should see that it was uploaded inside the newly created Sequence.
- Double click on the Video to edit its properties. On the Video Settings tab there should be an option to Upload a new video. Select your file and it will succesfully upload. If you want to add audio, activate the Audio Playback just below and adjust the volume to your needs. Click save to save your settings.
You can now repeat steps 2 and 3 to add the 2nd video (and any subsequent videos). The videos will play in the order they were uploaded (from top to bottom). Once a video ends, the other one will start automatically. If you want to move the videos around, make sure to select the Sequence, so that everything inside moves along with it.