The Weekend's Viewing: World War II: The Last Heroes, Sat, Channel 4Spooks, Sun, BBC1

What's an explosion for on television? World War II: the Last Heroes, Channel 4's series about the veterans of the war in Europe would like us to believe it has instructional purpose.

The point of the series as a whole, according to the opening voiceover, is tribute and corrective history. The veterans of the Second World War aren't getting any younger and soon, if not quite yet, it will be our "last chance to hear what really happened at first hand". What's offered here, we're told, is "their story in their words... not the one written by generals and historians". But then the introduction added an odd remark: "Where archive doesn't exist," it said, "we'll use real bombs and weapons to illustrate what our veterans went through." That's the essential promise: eye-witness testimony, newsreel footage and lots of explosions.

The testimony, as it almost always is in these things, was completely gripping. There might not be archive film of the moments these men recall, but you can tell from their words that a looped image is running in their heads, its details almost as crisp as the day on which the exposure was made. "As I hit the deck, a hand landed with me... a whole arm... and I screamed my head off," said Frank Rosier, then a young boy and encountering enemy fire for the first time in the Normandy bocage. Bill Evans, a Welsh soldier, laughingly recalled how he'd been known as 31 Evans, because so many men shared the same name in the Welsh regiments. And then his story darkened as he described how 36 Jones was killed after a splinter from a shelled tree hit him in the face. A tank-commander called John Cloudsley-Thompson remembered feeling the tingle of a shell from a Tiger tank passing between his parted legs to explode in the engine compartment behind him. "That's the only day I've been really frightened," he said, his voice trembling in recollection. "I was an adult by the end of it, but at the beginning I wasn't."

There were times when the explosions genuinely added information to these accounts. Footage of shells exploding in the canopies of trees, bringing down large branches and sharp splinters did give you some sense of the terror of such a moment. And to see the earth thump upwards, hundreds of yards from a bomb blast, brought home the power of an aerial assault. But there were more occasions when the percussion was troubling. After all, anyone who goes to the movies regularly these days will already know what an explosion looks like. It's what it feels like we aren't so familiar with and only words can convey that. An extreme slow-motion shot of a French kitchen being sprayed with machine-gun fire or a grenade going off isn't really an enlargement of our understanding of the horror of war. It's the pornography of violence, the kind of footage that attracts words like "cool" and "awesome" when it appears on YouTube. And what's most appalling about any explosion – its brutal speed – is repeatedly smeared out by slow-mo here until it's appealing. If that's the price you have to pay to get a contemporary audience to pay attention to these men's stories, perhaps it's worth paying. But one does wonder if the fee had to be quite so high.

Spooks has often relished the pleasure of a good explosion in the past, but it declined to go out on one, despite the promising possibility of shooting down a civilian airliner over central London. Instead, almost wistfully, it added one last victim to its long roster of in-house sacrifices, as Ruth took a shard of glass in the ribs and expired in Harry's arms. Matthew Macfadyen popped up again too, in a way that seemed to suggest he was a double, or possibly even a treble agent. I know many will regret its passing, but the best I can manage by way of eulogy, I'm afraid, is nil nisi bonum.