docs: added pairwise alignment GUI video

docs/computational/pairwise_alignment.md

@@ -183,11 +183,11 @@ We provide a video showcasing the GUI, with an illustrative example of refinemen
 __[Walkthrough of the GUI for manual alignment]__ by @danilexn – :octicons-clock-24:
 5m – Learn how to visualize and align STS and imaging data in a step-by-step guide.
 
-  [Walkthrough of the GUI for manual alignment]: https://www.youtube.com
+  [Walkthrough of the GUI for manual alignment]: https://youtu.be/Fjh4huosVPY
 
 ---
 
 ## Expected output
 After running the automatic or manual alignment, you must have a single `h5ad` file, containing the transformed spatial coordinates.
 This will be used in the following step to aggregate the transcripts by a spatially-corresponding cell, in order to get a cell-by-gene
-matrix that can be used in later downstream analysis.
+matrix that can be used in later downstream analysis.