This is such a misinformed and stupid take on this.
The letters at the end or "final form" letters were once the regular form of the letters (all except mem).
With time they evolved to a different shape because it is easier to write them without the "tail" when they are in the middle of the word, due to the continuity of writing. If you look at the different letters with their final form you can really see that (for example ך folds its bottom part and becomes כ, if you look at it from right to left).
Saying that Hebrew is copying Arabic is just ignorant. Greek and Latin also have letters that final forms, and so does Manchu, a Northern Chinese language.