Tinycitrus agree about the film of TBITSP. Even David Thewlis can't redeem the way they've buggered up showing the quiet horror of the ending.
Dustysparrow - I love that McKellen/Dench version, but it's classroom death. Far too spare & understated for ks3.
McKellen doing Richard III, on the other hand - awesome & I've used at KS3 & KS5.
You're right, it's not 'bloody difficult' to find a version of Macbeth that won't upset anyone.
But it's a 'bloody difficult' play, addressing difficult ideas in a bloody way.
I'm familiar with all the film versions (Sean Pertwee? Lame. James MacEvoy - interesting but not where you start, as it's a modern re-telling. Patrick Stewart - good in parts, but frankly if you don't approve of Polanski you really wouldn't like this one! Ian McKellen - amazing performance, but not engaging at school level. Animated Tales - brilliant animation, good starting point. Fassbender - just no. Awful) etc etc.
It's not as simple as 'oh there's obviously going to be a tamer version out there, so that will do just as well. They'll learn the plot & the teacher will get an easy lesson. Sorted'
If I'm showing students a film version of a text we are studying in class, it's because I think that version has something interesting to say about the themes & imagery OF the play.
I can't just substitute some random, polite BBC production. That wouldn't add anything to the purposes of studying this particular text in the first place. It needs to be engaging, & it needs to be provoking.