Issue #147. Report problems with videos

I don't consider this done, but I'd like @willkg to have a look at it.

For now the form is displayed on a separate page, I'm more careful now regarding modals - after a while the suggestions form, which started as modal, was changed.

**TODO**

- [ ] Documentation
- [ ] Tests
- [ ] Modal (?)
- [ ] Wording

I hope we can use this as a starting point and build upon it.