Oh now i see, Enouce MySpeed uses NPAPI extensions.
Chromium related brosers (like Vivaldi) do not support that anymore since more than a year.
Works for me with 1.11.917.43 Stable and 1.12.955.3 Snapshsot on Windows 10x64.
Which OS? Which Vivaldi version?
Do you use single key shortcuts in Vivaldi settings?
Which other extensions do you use?
Try to disable all others and enable Vimium only.
The URL vivaldi://flash shows some information which Flash plugin is running in which folder.
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