According to the following Chrome bug titled "Devtools websockets frames export", the Chrome developers intended that you be able use the clipboard to "copy" all frames selected across multiple screens in the Dev Tools > Network > WebSockets > Frames scroll area i.e.
- Using Microsoft Windows, Mouse-Left-Click on the first frame you want to copy export.
- Use the scrollbar, to scroll the WebSocket 'Frames' window down to the last frame you want.
- With the SHIFT key held, Mouse-Left-Click on the last frame.
- Mouse-Right-Click on the selected area and select "Copy" from the context menu (or simply type CTRL+C).
- Paste the copied frames to a text editor.
Currently this sequence only works if you omit #2.
Here's a link to the bug...
https://bugs.chromium.org/p/chromium/issues/detail?id=496006
The bug's status got set to "Started" on August 1, 2016 but as of February 16, 2017 has yet to be fixed. I'm testing with Chrome Version 56.0.2924.87.
I'd recommend Star'ing the bug to show interest in getting it fixed.