Is This Phishing?

I've been downloading comedy, documentary and recipe videos from youtube. The program I use is Free Youtube Downloader. You start viewing a video, right-click to copy the URL, and it immediately appears in the downloader address bar. Then you click to download as MP4. It will convert the video, if necessary. It's very handy.
But I've noticed that the addresses aren't precisely the same as the one I copied.

Example: I'm watching:

When it is copied, it shows up automatically on the downloader as:
https://youtu.be/PTqqiDQP02I
When I force my browser to go to this URL, it says the site can't be reached. I say "forced," because it sometimes goes to the first, correct, URL, thus taking out the period.

I am now erasing the period in the youtube name in the downloader, each time. I then get a list of videos, with the one I want usually at the top. Virtually every video I download comes out with that period in the middle of "youtube."

Am I being phished by the downloader? Or by youtube? Or by someone else?

If so, can the phishing be traced? Or eliminated from the source (browser or downloader)? I'm dealing with it now by simply erasing the period in the downloader address bar. But I still want to get answers to these questions. I'd like this habit to stop interfering with my downloads.

Thanks.