This was made shortly after WWII and it was on TV when I was in grade school in the 1950s. They gathered up all the news reel and movie film of the war, including film captured from the Germans and the Japanese, and spliced it all together to tell a coherent story. Richard Rodgers of Rogers and Hammerstein fame did the musical score, and it is a spectacular score. It's a good watch and it does not only the naval side of WWII but a does a fair job on the land and air wars too. It moves right along and kids will enjoy watching it. Your kids will have a better understanding of what WWII was about and how it was fought for watching it.
I picked up a 5 DVD set that has every episode from the "Cheap Old DVD" bin at Walmart some years ago. I don't know where you might find it today, but Googling for "Victory at Sea DVD" might turn something up.
The video is all black and white. Partly because color TV did not become widespread until the 1960s and largely because the color film of the day (Kodachrome) was so achingly slow, and only really worked out of doors on bright sunny days. The available black and white film was much faster (more sensitive to light) and less fussy about exposure settings. Even so, many of the video clips have the tops of everything burned in white and the sides and undercarriages solid black.
Anyhow, if you can find it, your children will enjoy it and they will learn something.