I also spent a lot of time researching for the proper equipment for recording the videos I wanted to include in 8-bit Memoirs.
I ended up buying an XRGB-mini Framemeister and a Hauppauge HD-PVR Rocket standalone recorder.
The Amstrad CPC signal then went into the XRGB-mini Framemeister, which took the 288p@50,08hz and converted it to 720p@50hz. The XRGB-mini Framemeister also allowed me to zoom and crop the image, so that I'm actually cutting the edges of the frame in order to get a real 1:3 size ratio. I.e. the 288p are multiplied by 3 = 864p, but then I cut off 72 pixels at the top and at the bottom. This lets me keep the crispy pixel-image.
This does require some time to set up, but it's totally worth it.
The Hauppauge HD-PVR Rocket has a single button that you press when you want to record, and press again when you want to stop recording. It records onto whatever USB device you plug into it. It's very nice. It also has a microphone plug, so you can record your voice while recording the video, and there's an input-level setting too.
The XRGB-Framemeister is awesome because it converts the 50,08 hz CPC output to a straight 50 fps video, which made it compatible with Blu-ray. Unfortunately, this also means that the audio won't match. So some post work is necessary: Count the number of frames in the video. Divide it with 50. That's how many seconds and milliseconds long the audio must be. Now load the audio into Audacity and chance the length of the audio to match those seconds and milliseconds.
And finally, I ran an FFMPEG command to apply an Amstrad CPC monitor filter, but you're probably not looking for something like that.