Method 1. How to Merge Video-Only Video File with Audio Using KeepVid Joiner
Hit the Download button to download KeepVid Joiner on your computer.
Please note that KeepVid Joiner needs .NET Framework 2.0 or higher to run KeepVid Joiner.
Now you'll get the ZIP file in your computer. Right-click the ZIP file and decompress it. When the process in finished, you'll get a folder. Double-click to open it.
You'll see an application named VidJoin. Now double-click to open it, and you'll see the main interface of this application.
Click the Browse button besides the Video Only section, and load the video you’ve downloaded. Then click the Browse button besides the Audio Only section to load the audio file from your computer as well.
After that, click the Join button at the middle-right part of the application. Then the application will start merging the video file with audio track. When the process finishes, you’ll get the video with audio file.
Method 2. How to Download HD Video with Audio Directly Using KeepVid Pro
Download and Install KeepVid Pro on your computer, then start it. The program will display the main interface of video downloading.
Go to YouTube and find the video you want to download. Then copy the video URL in the address bar.
Click the Paste URL button in KeepVid Pro, and the program will analyze the video URL, and display a pop-up dialog for you to select the video quality. Now select the video quality you want, and click the Download button.
Now KeepVid Pro will start downloading the video immediately. When the downloading process finishes, you’ll get the downloaded video in Downloaded tab.