Merge pull request #112998 from kromerm/adfdocsmark

Update data-flow-union.md

Author: PRMerger12

articles/data-factory/data-flow-union.md

@@ -7,7 +7,7 @@ ms.reviewer: douglasl
 ms.service: data-factory
 ms.topic: conceptual
 ms.custom: seo-lt-2019; seo-dt-2019
-ms.date: 02/12/2019
+ms.date: 04/27/2020
 ---
 
 # Azure Data Factory mapping data flow union transformation
@@ -18,6 +18,10 @@ Union will combine multiple data streams into one, with the SQL Union of those s
 
 You can combine n-number of streams in the settings table by selecting the "+" icon next to each configured row, including both source data as well as streams from existing transformations in your data flow.
 
+Here is a short video walk-through of the union transformation in ADF's mapping data flow:
+
+> [!VIDEO https://www.microsoft.com/en-us/videoplayer/embed/RE4vngz]
+
 ![Union transformation](media/data-flow/union.png "Union")
 
 In this case, you can combine disparate metadata from multiple sources (in this example, three different source files) and combine them into a single stream: