OK, first I want to mention photoshop does have fade options but I prefer keyframing, better control. (for me anyway)
1)Open the video
2)Select the video group in the layers panel and ungroup it. (for what you need the text layer must be above the video layer in the timeline panel. Grouped they are both on the same layer in the timeline making it easier to splice video)
3)Drag the text layer in the timeline over to about where you want it to start - we will assume at the start of the video for this example.
4)In the lower left corner of the timeline panel are number ex. 00:20:23 - Double click on it and set it to roughly 1 second in from the beginning of the text layer.
5)To the left of the name of the layer in the timeline is an arrow, click it to twirl it down.
6) Find Opacity and click the stopwatch icon to active animation for that effect
7) Click the circle between the two arrows. This will create a keyframe with an opacity of 100%
8) Move the timeline to 00:00:00 the in the layers panel set the opacity of that layer to 0
What happened was because the opacity was already at 100% it made sense to set that keyframe first. When you move timeline play head to a new location adjusting the opacity value creates the keyframe for you.
Now repeat for the opposite end of the text animation by moving the playhead to the end and click the circle to create the keyframe, then move the playhead in about a second and set the opacity back to 100% - in other words it should mirror the first two keyframes.
If you make any mistakes you can drag select the keyframes and delete them.