Remove the `\<time\>` tag and add it in as a variable along with a comment explaining it. Something like:

```jinja2
{% set submit_time = datetime(2013, 2, 28) %}
{# L10n: Describes the date that a video was submitted to the contest. #}
{% trans date='<time datetime="{0}">{1}</time>|f(submit_time.isoformat(), submit_time|babel_format) %}
  Submitted {{ date }}
{% endtrans %}
```