I had the same issue. I would recommend using the firefox add on “Web2PDF” It basically takes any web page and turns it into an ultra high res PDF. You can then take it into photoshop and chop it up any way you want. I used it with this piece https://vimeo.com/42387031 from the 00:10:00 to 00:17:00 second mark. I believe the plugin is free. https://www.web2pdfconvert.com/pdf-button#cid1