I became familiar with this carol a year ago. It is apparently sung commonly in the New England region during the Christmas season. The lyrics are provide below the video.
1. The tree of life my soul hath seen,
Laden with fruit and always green:
The trees of nature fruitless be
Compared with Christ the apple tree.
2. His beauty doth all things excel:
By faith I know, but ne’er can tell
The glory which I now can see
In Jesus Christ the apple tree.
3. For happiness I long have sought,
And pleasure dearly I have bought:
I missed of all; but now I see
‘Tis found in Christ the apple tree.
4. I’m weary with my former toil,
Here I will sit and rest awhile:
Under the shadow I will be,
Of Jesus Christ the apple tree.
5. This fruit doth make my soul to thrive,
It keeps my dying faith alive;
Which makes my soul in haste to be
With Jesus Christ the apple tree.